UC-NRLF 


B   4    hDD    MES 


FIRST  BOOK  OP  GRASSES 


Hurai 

EDITED  BY  L.  H.  BAILEY 

Bailey:  SCHOOL-BOOK  OF  FARMING. 

Carleton:  THE  SMALL  GRAINS. 

Chase:  FIRST  BOOK  OF  GRASSES. 

B.  M.  Duggar:  THE  PHYSIOLOGY  OF  PLANT 
PRODUCTION. 

J.  F.  Duggar:  AGRICULTURE  FOR  SOUTHERN 
SCHOOLS. 

J.  F.  Duggar:  SOUTHERN  FIELD  CROPS. 

Fisk:  THE  BOOK  OF  ICE-CREAM. 

Gay:  BREEDS  OF  LIVE-STOCK. 

Gay:  PRINCIPLES  AND  PRACTICE  OF  JUDGING 
LIVE-STOCK. 

Goff:  PRINCIPLES  OF  PLANT  CULTURE. 

Gourley:  TEXT-BOOK  OF  POMOLOGY. 

Guthrie:  THE  BOOK  OF  BUTTER. 

Harper:  ANIMAL  HUSBANDRY  FOR  SCHOOLS. 

Harris  and  Stewart:  THE  PRINCIPLES  OF 
AGRONOMY. 

Hitchcock:  TEXT-BOOK  OF  GRASSES. 

Jeffery:  TEXT-BOOK  OF  LAND  DRAINAGE. 

Jordan:    FEEDING    OF    ANIMALS,    REVISED. 

Livingston:  FIELD  CROP  PRODUCTION. 

Lyon:  SOILS  AND  FERTILIZERS 

Lyon,  Pippin  and  Buckman:  SOILS;  THEIR 
PROPERTIES  AND  MANAGEMENT. 

Mann:  BEGINNINGS  IN  AGRICULTURE. 

Montgomery:  THE  CORN  CROPS. 

Morgan:  FIELD  CROPS  FOR  THE  COTTON- 
BELT. 

Mumford:  THE  BREEDING  OF  ANIMALS. 

Piper:  FORAGE  PLANTS  AND  THEIR  CULTURE. 

Sampson:    EFFECTIVE    FARMING. 

Smith:  AGRICULTURAL  METEOROLOGY. 

Stubenrauch,  Wood  and  Booth:  HORTICULTURE 
FOR  SCHOOLS. 

Thorn  and  Fisk:  THE  BOOK  OF  CHEESE. 

Warren:  ELEMENTS  OF  AGRICULTURE. 

Warren:  FARM  MANAGEMENT. 

W heeler:  MANURE  AND  FERTILIZERS. 

White:  PRINCIPLES  OF  FLORICULTURE. 

Widtsoe:  PRINCIPLES  OF  IRRIGATION  PRAC- 
TICE. 


FIRST  BOOK  OF 


THE  STRUCTURE  OF  GRASSES  EXPLAINED 
FOR  BEGINNERS 


PY 

AGNES  CHASE 

ASSISTANT  AGROSTOLOGIST,  UNITED  STATES  DEPARTMENT 
OF  AGRICULTURE 


•Bforo  f  0rk 

THE  MACMILLAN  COMPANY 
1922 

All  rights  reserved 


QK4ci5 


UBR^RY 
G 


COPYRIGHT,  1922 
BY  THE  MACMILLAN  COMPANY 


Set  up  and  electro  typed.     Published  November,  1922. 

AGRIG,  DEPh    ftr^4rH   D.V. 


Printed  in  the  United  States  of  America 


PREFACE 

Of  all  plants  grasses  are  the  most  important  to 
man.  The  different  kinds  are  known  by  very  few 
even  among  botanists.  This  is  largely  because  they 
are  supposed  to  be  very  difficult.  When  the  struc- 
ture of  grasses  is  clearly  understood,  they  are  not 
more  difficult  to  study  than  are  other  plants.  The 
method  here  offered  has  been  used  by  the  author  for 
some  years  in  teaching  special  students. 

The  introduction  explains  the  method  followed. 
The  body  of  the  primer  consists  of  twelve  lessons, 
graded  from  the  simplest  to  the  most  complex. 
Each  lesson  is  accompanied  by  figures  bringing  out 
the  facts  in  the  text.  The  difference  in  the  size 
of  the  flowering  organs  is  so  great  that  the  figures 
are  not  drawn  to  the  same  scale.  The  organs  are 
enlarged  as  much  as  necessary  to  illustrate  the  char- 
acter discussed. 

Grasses  of  the  United  States  are  used  for  the  lessons 
and  the  commoner  ones  are  selected  so  far  as  possible; 
however,  our  native  grasses  cover  so  wide  a  range 
that  the  principles  laid  down  in  the  lessons  are  ap- 
plicable to  grasses  generally. 

AGNES  CHASE. 

Washington,  D.  C.,  August  10,  1922. 

494313 


TABLE   OF   CONTENTS 

PAGES 
INTRODUCTION 1-7 

Use  of  technical  terms,  2;  Use  of  Latin  names,  4;  Tools 

needed,  6. 
LESSON  I 8-16 

The  grass  family,  8;  Summary,  16;  Review,  16. 
LESSON  II 17-20 

The  spikelet  and  the  inflorescence,  17;  Summary,  19; 

Review,  20. 
LESSON  III 21-24 

Modifications  of  the  spikelet,  21;  Summary,  24. 
LESSON  IV 25-33 

Pediceled  spikelets  of  few  to  many  florets,  25;  Sum- 
mary, 33;  Review,  33. 
LESSON  V 34-41 

Sessile  spikelets  in  two-sided  spikes,  34;  Summary,  41; 

Review,  41. 

LESSON  VI 42-45 

Pediceled  spikelets  with  large  glumes  and  other  modi- 
fications, 42;  Summary,  45;  Review,  45. 

LESSON  VII 46-53 

Pediceled  one-flowered  spikelets,  46;  Summary,  52; 
Review,  53. 

LESSON  VIII 54-60 

Sessile  spikelets  in  one-sided  spikes,  54;  Summary,  60; 
Review,  60. 

LESSON  IX 61-67 

Diversely  specialized  spikelets,  61;  Summary,  67;  Re- 
view, 67. 

vii 


viii  TABLE  OF  CONTENTS 

PAGES 
LESSON  X 68-78 

Spikelets  with  membranaceous  glumes  and  hardened 

fruits,  68;  Summary,  77;  Review,  78. 
LESSON  XI 79-88 

Paired    spikelets    with    hardened    glumes    and    thin 

lemmas,  79;  Summary,  88;  Review,  88. 
LESSON  XII 89-94 

Highly  specialized  unisexual  spikelets,  89;  Summary, 

94;  Review,  94. 
DIAGRAMMATIC  SUMMARY  OF  THE  PRIMARY  CHARACTERS 

OF  THE  TRIBES 95-99 

Series  1,  Poatse,  95;  Series  2,  Panicatse,  98. 
GENERAL  INFORMATION  FOR  THE  BEGINNER 100-115 

Outline  for  study  of  a  grass  plant,  100;  Books,  104; 

Botanical  names,  108;  Classification  of  plants,  111; 

Position  of  grasses  in  the  plant  kingdom,  113;  Grasses 

in  relation  to  man,  114. 


LIST   OF   ILLUSTRATIONS 

FIG.  PAGE 

1.  Vegetative  part  of  a  grass  plant;  part  of  leaf  opened  out. .     9 

2.  Typical  complete  flower  showing  calyx,  corolla,  stamens 

and  pistils 9 

3.  Grass  flower,  showing  stamens  and  pistil  and  the  rudi- 

ments of  floral  envelope 10 

4.  A  floret  at  flowering  time 11 

5.  Two  views  of  a  grain 11 

6.  Diagram  of  a  flowering  branch 12 

7.  Diagram  of  a  grass  spikelet 12 

8.  Generalized  spikelet 13 

9.  Base  of  plant  and  underground  parts,  roots  and  rhizomes, 

of  Poa  pratensis 14 

10.  Forms  of  inflorescence;  A,  panicle;  B,  raceme;  C,  spike..   18 

11.  A,  several-flowered  spikelet  of  Bromus  secalinus;  B,  single 

floret 25 

12.  A,  spikelet  of  Festuca  ovina;  B,  lemma  detached 26 

13.  Spikelet  of  Panicularia  septentrionalis 27 

14.  Spikelet  of  Poa  pratensis 27 

15.  Palea  of  Pleuropogon  californicus 27 

16.  Floret  of  Triodiaflava 28 

17.  Lemma  of  Cottea  pappophoroides 28 

18.  A,  spikelet  of  Phragmites  communis;  B,  floret 28 

19.  Spikelet  of  Melica  mutica 29 

20.  Florets  of  Pappophorum  vaginatum 29 

21.  A,  part  of  a  panicle  of  Cynosurus  cristatus;  B,  sterile 

spikelet;  C,  fertile  spikelet 30 

22.  A,  fascicle  of  three  sterile  and  one  fertile  spikelet  of 

Achyrodes  aureum;  B,  fertile  spikelet 31 

23.  Pistillate  and  staminate  spikelets  of  Distichlis  spicata.  . .  32 

ix 


x  LIST  OF  ILLUSTRATIONS 

FIG.  PAGE 

24.  Staminate  and  pistillate  spikelets  of  Scleropogon  brevi- 

folius 32 

25.  A,  part  of  a  spike  of  Agropyron  repens;  B,  part  of  rachis 

seen  from  the  edge,  all  but  two  spikelets  removed ....  34 

26.  Spikelet  of  Triticum  cestivum 35 

27.  Part  of  a  spike  of  Lolium  multiflorum 36 

28.  A,  part  of  a  spike  of  Lepturus  cylindricus;  B,  diagram  of 

rachis,  spikelets  removed;  above,  diagram  of  single 
joint 37 

29.  A,  pair  of  spikelets  of  Elymus  virginicus;  B,  diagrammatic 

figure  of  the  pair  of  spikelets 38 

30.  Joint  of  spike  of  Hordeum  nodosum 40 

31.  A,  spikelet  of  Avena  fatua;  B,  floret 42 

32.  Spikelet  of  Trisetum  spicatum 43 

33.  Spikelet  of  Danthonia  spicata;  floret  above 43 

34.  A,  spikelet  of  Notholcus  lanatus;  B,  pair  of  florets 44 

35.  Spikelet  of  Calamagrostis  canadensis 46 

36.  Spikelet  of  Agrostis  hiemalis 47 

37.  Spikelet  of  Sporobolus  airoides 47 

38.  Spikelet  of  Phleum  pratense;  floret  above 48 

39.  Spikelet  of  Alopecurus  geniculatus 48 

40.  Pair  of  spikelets,  sterile  and  fertile  (spread  apart)  of 

Lycurus  phleoides 49 

41.  Spikelet  of  Muhlenbergia  foliosa 50 

42.  A,  spikelet  of  Muhlenbergia  Schreberi;  B,  branchlet  with 

the  minute  glumes  of  two  spikelets  from  which  florets 

have  fallen 50 

43.  A,  spikelet  of  Milium  effusum;  B,  floret 50 

44.  A,  glumes,  and  B,  floret  of  Oryzopsis  racemosa 51 

45.  A,  glumes,  and  B,  floret  of  Stipa  spartea 51 

46.  Spikelet  of  Aristida  dichotoma 51 

47.  A,  spikelet  of  Eleusine  indica;  B,  inflorescence 55 

48.  A,  spikelet  of  Capriola  Dactylon;  B,  inflorescence 55 

49.  A,  spikelet  of  Chloris  latisquamea;  B,  fertile  lemma  spread 

out;  C,  sterile  lemma  spread  out;  D,  inflorescence. ...  56 


LIST  OF  ILLUSTRATIONS  xi 

FIG.  PAGE 

50.  A,  spikelet  of  Bouteloua  curtipendula;  B,  fertile  lemma 

spread  out;  C,  sterile  lemma  spread  out;  D,  inflores- 
cence    57 

51.  A,  spikelet  of  Bouteloua  gracilis;  B,  fertile  lemma  spread 

out;  C,  first  sterile  lemma  spread  out;  D,  second  sterile 
lemma  spread  out;  E,  inflorescence 58 

52.  A,  fascicle  of  Mgo'pogon  tenellus;  B,  lemma,  and  C,  palea, 

spread  out,  of  the  sterile  spikelet;  D,  lemma  and  E, 
palea  of  perfect  spikelet 61 

53.  A,  fascicle  of  Hilaria  Belangeri;  B,  glumes  of  staminate 

spikelet;  C,  two  views  of  the  perfect  spikelet;  D,  fertile 
floret 62 

54.  A,  bur-like  fascicle  of  Nazia  aliena;  B,  single  spikelet; 

C,  floret 63 

55.  A,  spikelet  of  Anthoxanthum  odoratum;  B,  pair  of  sterile 

florets  below  the  perfect  floret;  C,  perfect  floret 64 

56.  A,  spikelet  of  Phalaris  canariensis;  B,  fertile  floret  with 

pair  of  small  sterile  florets  attached  at  the  base 65 

57.  Spikelet  of  rice  (Oryza  saliva) 66 

58.  Spikelet  of  Homalocenchrus  oryzoides 66 

59.  A,  pistillate  spikelet,  and  B,  staminate  spikelet  of  Zizania 

paluslris 66 

60.  A,  spikelet  of  Panicum  miliaceum,  side  view;  B,  same 

seen  from  the  back;  C,  sterile  and  fertile  florets  removed 
from  the  glumes,  side  view;  D,  fertile  floret 69 

61.  A,  two  views  of  spikelet  of  Synlherisma  sanguinalis; 

B,  fertile  floret;  C,  inflorescence 70 

62.  A,  two  views  of  spikelet  of  Paspalum  loeve;  B,  fertile 

floret;  C,  inflorescence 71 

63.  A,  rachis  of  Paspalum  Iceve,  spikelets  removed;  B,  rachis 

of  a  Paspalum  with  paired  spikelets;  C,  cross-section  of 
rachis,  showing  raised  center  and  thin  margins 71 

64.  A,  part  of  a  raceme  of  Stenolaphrum  secundalum,  front 

view    showing    spikelets;    B,   back    view    of    three 
joints 72 


xii  LIST  OF  ILLUSTRATIONS 

FIG.  PAGE 

65.  A,  part  of  raceme  of  Axonopusfurcatus;  B,  inflorescence; 

C,  cross-section  of  rachis 73 

66.  A,  spikelet  of  Erlochloa  punctata;  B,  fertile  floret 73 

67.  A,  diagrammatic  panicle;  B,  two  branches  of  panicle 

with  terminal  spikelets  removed 74 

68.  Small  part  of  bristly  panicle  of  Chcetochloa  Grisebachii . .  74 

69.  A,  fascicle  from  panicle  of  Chcetochloa  lutescens;  B,  spike- 

like  panicle  of  same 75 

70.  Bur  of  Cenchrus  myosuroides 76 

71.  Bur  of  Cenchrus  pauciflorus 76 

72.  Base  of  plant  of  Amphicarpon  Purshii 77 

73.  A,  two  views  of  single  joint  of  raceme  of  Holcus  halepen- 

sis;  B,  diagram  of  raceme  of  four  joints;  C,  diagram 
of  rachis  and  pedicels 80 

74.  A,  diagram  of  single  joint  of  raceme  of  Erianthus  sac- 

charoides;  B,  three  joints  of  raceme 81 

75.  A,  single  joint  of  a  raceme  of  Andropogon  scoparius;  B, 

small  part  of  compound  inflorescence 82 

76.  A,  single  joint  of  raceme  of  Manisuris  cylindrica;  B, 

another  view  of  two  joints;  C,  inner  face  of  rachis  joint 
and  pedicel,  spikelet  removed;  D,  part  of  cylindrical, 
many-jointed  raceme , 83 

77.  A,  single  joint  of  raceme  of  Rytilix  granularis;  B,  reverse 

view;  C,  diagram  of  rachis  and  pedicels  of  three  joints 
of  raceme,  spikelets  removed;  D,  view  of  inner  face  of 
first  glume  of  sessile  spikelet;  E,  raceme;  F,  reverse 
view 84 

78.  A,  one-jointed  raceme  of  Rhaphis  pauci flora;  B,  base  of 

raceme  and  summit  of  branch;  C,  the  hairy  summit  of 
branch  from  which  raceme  has  fallen;  D,  inflorescence  86 

79.  A,  single  joint  of  raceme  of  Heteropogon  contortus;  B,  per- 

fect spikelet  from  which  sterile  spikelet  has  fallen;  C, 
base  of  fertile  spikelet  and  its  callus;  D,  raceme;  E, 
diagram  of  a  raceme;  F,  diagram  of  rachis  and  pedicels 
of  four  joints  of  raceme 86 


LIST  OF  ILLUSTRATIONS  xiii 

FIG.  PAGE 

80.  A,  two  joints  of  pistillate  part  of  raceme  of  Tripsacum 

dactyloides;  B,  spikelet  removed  from  the  joint;  C, 
rachis  joint  from  which  the  spikelet  has  been  removed; 
D,  inflorescence;  E,  diagram  of  rachis  of  pistillate  part; 
F,  pair  of  stamin  ate  spikelets 89 

81.  A,  part  of  a  cross  section  of  an  ear  of  corn,  Zea  Mays, 

showing  two  pistillate  spikelets  standing  at  right  angles 
to  their  axis  (the  cob);  B,  pistillate  spikelet  about 
flowering  time;  C,  part  of  raceme  of  staminate  spikelets  91 

82.  A,  pistillate  inflorescence  of  Bulbilis  dactyloides;  B,  pis- 

tillate spikelet  cut  from  the  rachis;  C,  pistillate  floret; 
D,  diagram  of  half  a  head,  showing  one  of  the  two  rows 
of  spikelets;  E,  staminate  inflorescence;  F,  staminate 
spikelet 92 

83.  Diagram  of  inflorescence  of  Festucea3 95 

84.  Diagram  of  inflorescence  of  Hordese 95 

85.  Diagram  of  inflorescence  of  Avenea3 95 

86.  Diagram  of  inflorescence  of  Agrostideae 96 

87.  Diagram  of  inflorescence  of  Chloride* 96 

88.  Diagram  of  inflorescence  of  Naziese 96 

89.  Diagram  of  inflorescence  of  Phalaridese 97 

90.  Diagram  of  inflorescence  of  OryzeaB 97 

91.  Diagram  of  inflorescence  of  Zizaniese 97 

92.  Diagram  of  inflorescence  of  Paniceae 98 

93.  Diagram  of  inflorescence  of  Andropogonea? 99 

94.  Diagram  of  inflorescence  of  Tripsacese 99 


FIRST  BOOK  OF  GRASSES 


FIRST  BOOK  OF  GRASSES 

INTRODUCTION 

THE  purpose  of  this  primer  is  to  give  those  with 
little  or  no  knowledge  of  botany  such  an  understand- 
ing of  the  structure  of  grasses  as  will  enable  them  to 
use  manuals  of  botany  and  other  technical  works, 
to  the  end  that  our  native  grasses  may  become 
better  known  and  their  worth  and  beauty  be  more 
fully  appreciated. 

The  best  method  of  studying  any  organisms  is  to 
observe  and  examine  the  organisms  themselves. 
Since  these  can  not  be  provided  in  a  book,  drawings 
of  the  objects  studied  are  here  offered  as  the  best 
substitute.  These  drawings  are  purposely  somewhat 
diagrammatic  in  order  to  bring  out  particular  char- 
acters that  may  be  less  prominent  in  the  actual 
plants.  While  the  drawings  convey  clearer  ideas  of 
structure  than  can  words  and  are  to  be  used  con- 
stantly with  the  text,  they  can  but  inadequately 
take  the  place  of  the  plants  themselves.  The  student, 
therefore,  should  collect  for  study  as  many  different 
kinds  of  living  grasses  as  possible. 

The  idea  of  a  primer  has  been  kept  in  mind.  The 
subject  is  presented  as  simply  as  possible,  and  only 
enough  grasses  are  examined  in  each  lesson  to  illus- 

1 


FIRST  BOOK  OF  GRASSES 

different  modifications  and  to  prepare  the 
student  to  comprehend  the  greater  modifications 
shown  in  subsequent  lessons. 

The  classification  of  grasses,  that  is,  the  grouping 
together  of  related  forms,  is  based  on  the  characters 
of  the  aggregate  of  minute  flowers  and  bracts  known 
as  the  spikelet.  It  is  necessary,  therefore,  for  anyone 
who  wishes  to  be  able  to  identify  a  given  grass  to 
understand  the  structure  and  modifications  of  the 
spikelet.  This  primer  is  really  an  elementary  study 
of  the  morphology  of  the  spikelet.  [Morphology  is  a 
branch  of  science  that  treats  of  form  and  structure. 
The  study  of  the  morphology  of  the  spikelet  enables 
one  to  recognize  its  various  organs  under  whatever 
form  they  may  assume.] 

USE   OF  TECHNICAL  TERMS 

Many  persons  who  might  otherwise  make  an 
effort  to  learn  something  about  our  common  wild 
flowers  and  trees,  as  well  as  grasses,  are  deterred 
by  the  sight  of  the  unfamiliar  words  used  in  botanical 
descriptions.  This  supposed  lion  in  the  way,  if  one 
will  but  draw  near  enough  to  see,  is  only  a  "harmless 
necessary  cat."  No  boy  learns  a  trade,  no  girl 
learns  to  sew  without  learning  the  names  of  the  tools 
used.  Words  like  hames,  whippletree,  terrets,  and  a 
hundred  more,  meaningless  to  the  city-bred  rider  on 
a  trolley-car,  are  familiar  terms  to  the  farmer.1  Such 

1  Mark  Twain's  description  (in  "A  Tramp  Abroad  ")  of 
how  they  hitch  horses  in  Europe  is  a  good  example  of  the  con- 


INTRODUCTION  3 

terms  as  carburetor,  accelerator,  clutch,  spark-plug 
or  magneto,  unknown  a  few  years  ago,  are  now 
understood  by  nearly  everyone,  and  those  who  do 
not  as  yet  understand  these  terms  are  by  no  means 
deterred  thereby  from  buying  (or  wishing  for)  an 
automobile.  Spikelet,  glume,  and  lemma  are  words 
no  more  difficult  to  learn  than  are  hames,  crupper, 
or  whippletree,  carburetor,  clutch,  or  magneto.  The 
reason  for  using  these  botanical  terms  is  the  same  as 
that  for  using  the  names  of  the  different  parts  of  a 
harness;  they  are  simpler  and  more  exact  than 
would  be  a  descriptive  phrase.  It  is  simpler  to  say 
"tenets"  than  to  say  "the  rings  that  stick  up  in  the 
middle  of  the  harness  on  the  horse's  back  that  you 
pass  the  reins  through"  and  it  is  simpler  to  say 

fusion  caused  by  want  of  technical  terms:  "The  man  stands 
up  the  horses  on  each  side  of  the  thing  that  projects  from  the 
front  end  of  the  wagon,  throws  the  gear  on  top  of  the  horses,  and 
passes  the  thing  that  goes  forward  through  a  ring,  and  hauls 
it  aft,  and  passes  the  other  thing  through  the  other  ring  and 
hauls  it  aft  on  the  other  side  of  the  other  horse,  opposite  to  the 
first  one,  after  crossing  them  and  bringing  the  loose  end  back, 
and  then  buckles  the  other  thing  underneath  the  horse,  and 
takes  another  thing  and  wraps  it  around  the  thing  I  spoke  of 
before,  and  puts  another  thing  over  each  horse's  head,  and  puts 
the  iron  thing  in  his  mouth,  and  brings  the  ends  of  these  things 
aft  over  his  back,  after  buckling  another  one  around  under  his 
neck,  and  hitching  another  thing  on  a  thing  that  goes  over  his 
shoulders,  and  then  takes  the  slack  of  the  thing  which  I  men- 
tioned a  while  ago  and  fetches  it  aft  and  makes  it  fast  to  the 
thing  that  pulls  the  wagon,  and  hands  the  other  things  up  to 
the  driver." 


4  FIRST  BOOK  OF  GRASSES 

" glume"  when  speaking  of  that  organ  of  a  grass  than 
to  say  "the  little  green  scale  on  the  outside  of  the 
thing  with  the  seed  in  it." 

In  the  first  lesson  nearly  all  the  new  words  that  a 
study  of  grasses  will  require  are  explained  and  illus- 
trated by  figures.  The  few  additional  terms  neces- 
sary are  explained  as  they  are  used.  No  attempt  is 
made  to  write  a  primer  of  grasses  in  words  of  one 
syllable  nor  to  produce  a  work  on  { i  how  to  know  the 
grasses"  without  mental  effort.  It  can  not  be  done. 


USE   OF   LATIN   NAMES 

Besides  unfamiliar  terms  there  are  the  unfamiliar 
Latin  names  of  the  plants  which  some  hesitate  to 
encounter.  But  many  of  the  names  in  common  use 
for  trees  and  herbs  are  the  botanical  names.  Mag- 
nolia, Rhododendron,  Petunia,  Asparagus,  Chrysan- 
themum, Phlox  are  the  Latin  botanical  names  and 
are  freely  used  by  all  without  hesitation.  Panicum, 
Paspalum,  Bromus,  Festuca,  Hordeum  are  no  more 
difficult.  As  in  the  case  of  such  terms  as  glume  and 
lemma,  the  Latin  names  of  plants  are  used  for  the 
sake  of  exactness.  Common  names  of  plants,  espe- 
cially of  those  which  are  useful,  troublesome,  or 
conspicuous,  are  more  definitely  applied  in  older 
countries  where  the  inhabitants  have  dwelt  in  a 
region  for  many  generations  than  they  are  with  us. 
Our  ancestors  brought  names  of  old  world  plants 
with  them  to  their  new  homes  and  applied  them  to 


INTRODUCTION  5 

plants  something  like  the  familiar  ones.  Conse- 
quently, many  common  names  are  used  in  different 
parts  of  the  country  for  widely  different  plants.  In 
Illinois  " June-grass"  is  Kentucky  blue-grass  (Poa 
pratensis),  a  valuable  pasture  grass;  in  Maine  "  June- 
grass77  is  Danihonia  spicata,  an  almost  worthless 
little  relative  of  wild  oats;  and  in  parts  of  the  West 
it  is  Kceleria  cristata.  The  name  " blue-joint77  is 
used  for  three  very  unlike  grasses.  On  the  other 
hand,  many  plants  have  different  names  in  separate 
parts  of  the  country.  Around  Washington,  D.  C., 
for  example,  Azalea  is  commonly  called  "  honey- 
suckle.77 Many  economic  plants  (such  as  potato, 
turnip,  and  rye)  have  common  names  uniform  in 
any  one  language  but  different  in  distinct  languages. 
When  the  Latin  name  of  a  plant  is  used,  it  is  definitely 
understood  not  only  throughout  the  United  States 
but  throughout  the  world  what  species  is  referred 
to.  However,  the  primary  reason  for  using  the 
botanical  names  is  that  these  indicate  the  relation- 
ship of  the  plants.  All  plants  of  a  kind  have  the 
same  genus  (or  generic)  name.  [Genus  is  the  sin- 
gular, genera  the  plural,  generic  the  adjective.] 
Kentucky  blue-grass  and  all  its  kind  are  Poa:  P. 
pratensiSj  P.  trivialis,  P.  annua,  P.  Sandbergii,  and 
so  on.  The  common  names  of  these,  Kentucky 
blue-grass  or  June-grass,  rough  meadow-grass,  spear- 
grass,  little  bunch-grass,  respectively,  give  no  clue 
to  their  relationship  or  kind.  Knowing  Poa  pratensis 
anyone  hearing  of  any  grass  named  Poa  has  an  idea 


6  FIRST  BOOK  OF  GRASSES 

of  what  it  is  like;  it  is  something  like  Poa  pratensis. 
Some  common  names,  especially  those  of  trees, 
indicate  the  kind:  Oak,  with  black,  white,  scarlet, 
swamp,  and  post  oak,  for  example,  and  also  hickory 
and  ash;  but  for  herbs,  and  especially  grasses,  the 
common  name  usually  gives  no  indication  of  the 
kind  of  plant  it  refers  to.  Often  the  name  is  mis- 
leading. Rib-grass  is  not  a  grass,  but  a  plantain; 
poison  ivy  is  not  an  ivy,  but  a  sumach.  To  convey 
definite  ideas  we  must  use  definite  terms  and  definite 
names. 

TOOLS   NEEDED 

Any  work  that  one  engages  in  requires  tools.  For 
the  study  of  grasses  we  need  but  few.  Grass  flowers 
are  too  small  to  be  seen  distinctly  with  the  naked 
eye.  A  lens  magnifying  about  ten  diameters  is 
necessary.  This  may  be  mounted  on  a  stand  or  it 
may  be  a  hand  lens.  A  simple  dissecting  microscope 
with  two  or  three  lenses  of  different  magnification 
would  be  more  convenient  and  would  well  repay  the 
cost,  but  it  is  not  absolutely  necessary.  If  one  has 
only  a  hand  lens,  an  eye-piece,  such  as  watchmakers 
place  in  the  eye,  will  also  be  found  very  useful  in  dis- 
secting, as  it  leaves  both  hands  free.  One  or  two 
dissecting  needles  are  needed.  These  can  be  made 
by  forcing  the  heads  of  coarse  sewing  needles  into 
a  pencil-shaped  piece  of  soft  wood.  After  some  prac- 
tice one  learns  to  use  the  nail  of  the  left  forefinger 
skilfully  in  dissecting.  One  can  work  more  rapidly 


INTRODUCTION  7 

with  this  and  one  needle  than  with  a  pair  of  needles. 
A  scalpel  is  useful,  but  the  small  sharp  blade  of  a 
penknife  will  answer  instead.  It  is  well  to  have  a 
piece  of  black  paper  or  cardboard  on  which  to  place 
hairy  spikelets.  The  hairs  on  the  different  parts 
show  up  well  against  this  background. 

It  is  the  aim  to  use,  so  far  as  possible,  the  charac- 
ters that  may  be  seen  in  the  different  parts  of  the 
spikelet  with  but  little  dissection.  When  further  dis- 
section is  necessary,  instructions  will  be  given  at  the 
end  of  the  lesson  requiring  it. 


LESSON  I 
THE   GRASS  FAMILY 

To  most  persons  grass  is  almost  any  green  vegeta- 
tion of  rather  low  growth,  especially  such  as  may  be 
grazed.  To  the  student  of  plants,  a  grass  is  a 
member  of  the  natural  family  Poacese,  or  Graminese, 
distinguished  by  its  structure. 

Grasses  are  herbs  with  round  or  flattened  (never 
3-angled),  usually  hollow  stems  (culms)  solid  at 
the  joints  (nodes),  and  2-ranked,  alternate,  parallel- 
veined  leaves,  composed  of  two  parts,  the  sheath, 
which  surrounds  the  culm  like  a  tube  split  down  one 
side,  and  the  blade,  which  is  usually  strap-shaped, 
flat,  folded,  or  with  rolled  margins.  At  the  junction 
of  the  sheath  and  blade,  on  the  inside,  is  a  small 
appendage  (the  ligule);  this  is  commonly  thin  in 
texture;  sometimes  it  is  only  a  ring  of  hairs,  rarely 
it  is  obsolete.  The  plants  may  be  annual  or  peren- 
nial. The  root,  stem,  and  leaves  are  the  vegetative 
part  of  the  plant  (Fig.  1).  These  are  all  that  are 
concerned  with  the  life  of  the  individual  plant.  The 
flowers  have  to  do  with  perpetuating  the  species. 
In  grasses  the  vegetative  parts  are  more  uniform 
and  characteristic  than  in  most  other  families. 

Having  stem  and  leaves  of  any  plant,  it  can  always 
be  readily  decided  whether  or  not  it  is  a  grass.  The 

8 


THE  GRASS  FAMILY 


FIG.  2.  Typical  complete 
flower,  showing   calyx, 
corolla,     stamens    and 
'  pistils. 

only  plants  that  may  rea- 
sonably be  mistaken  for 
grasses  are  the  sedges.    In 
these  the  culms  are  solid  or 
pithy,  are  not  jointed,  and  are 
commonly  3-sided;  the  leaves 
are  always  3-ranked,  and  the 
sheaths  always  closed. 

The  flowers  of  grasses 
are  small  and  inconspicuous. 
They  consist  of  a  single  pistil 
with  a  1 -celled,  1-ovuled  ovary, 
two  styles,  each  with  a  feath- 
ery stigma,  and  three  (rarely 
one  or  six)  stamens  with  deli- 
cate filaments  and  2-celled 
anthers.  Two  minute  scales, 
called  lodicules,  situated  back 

FIG.  1.  Vegetative  part  of  a    °f  the  Pistil>  at  blooming  time 

grass  plant;  part  of  leaf  become  turgid  and  force  open 

opened  out.  ,       .  , 

the  enveloping  scales. 
In  Fig.  2  are  shown  the  parts  of  a  common  flower 


10 


FIRST  BOOK  OF  GRASSES 


(the  wild  prairie  rose  with  long  styles).  The  calyx 
and  corolla  are  the  floral  envelopes;  the  stamens  and 
pistils  are  the  essential  organs  of  a  flower,  the  parts 
that  produce  seed.  The  floral  envelopes  protect 
the  essential  organs  in  the  bud  and,  by  secreting 
nectar  which  attracts  insects  or  in  other  ways,  com- 
monly aid  in  securing  the  fertilization  of  the  flower. 

The  pistil  consists  of  the 
ovary,  style,  and  stigma. 
The  ovary  contains  the 
ovules,  which  when  fer- 
tilized develop  into  the 
seeds.  The  style  serves 
to  lift  the  stigma  into  the 
air.  The  stigma  is  more 
or  less  expanded,  has  a 
viscid  surface  to  which 
FIG.  3.  Grass  flower,  showing  sta-  the  pollen-grains  adhere 


minate,  sending  their  con- 
tents in  a  minute  tube  which  pushes  down  through 
the  style  to  the  ovules,  fertilizing  them. 

The  grass  flower  (Fig.  3)  is  reduced  to  the  essential 
organs,  the  floral  envelopes  being  represented  by  the 
minute  lodicules.  Each  flower  is  borne  in  the  axil 
of  a  small  green  bract  (the  lemma)  and  is  subtended 
and  enveloped  in  a  second  bract  (the  palea).  The 
flower  with  its  lemma  and  palea  is  termed  the  floret 
(Fig.  4).  The  ripened  ovary  (the  grain,  or  caryppsis) 
(Fig.  5)  consists  of  a  small  embryo  lying  at  the  base 


THE  GRASS  FAMILY 


11 


of  a  mass  of  starchy  endosperm.  [Endosperm  means 
within  the  sperm  or  seed.  It  is  the  store  of  food 
used  by  the  infant  plantlet  when 
it  begins  to  grow.]  ^The  "germ"  of 
a  kernel  of  corn  is  the  embryo, 
while  the  remainder  of  the  kernel 
is  starchy  endosperm.  The  grain 
lies  in  the  palea  with  the  hilum 
(the  scar  of  the  point  of  attach- 
ment) toward  it,  and  the  embryo  ^ 
on  the  side  toward  the  lemma.  *' 
Fig.  5  gives  two  views  of  a  grain,  FlG-  4;rfng°t^eat  flow" 
one  showing  the  hilum,  the  other 
the.  embryo.  In  Fig.  81,  A  (page  91),  are  two  ker- 
nels of  corn  showing  the  embryos.  The  grain  with 
very  few  exceptions  is  permanently  in- 
closed in  the  lemma  and  palea,  the  ma- 
ture floret  being  the  fruit,  that  is,  the 
seed  with  its  permanent  envelopes.  The 
florets  are  borne  in  two  ranks  and  alter- 
nate upon  an  axis  (the  rachilla).  Below 
them  are  two  bracts  without  flowers 
(the  glumes).  The  glumes,  rachilla,  and 
florets  together  form  the  spikelet. 

Fig.  6  is  a  diagram  of  a  branch  with 
leaves  and  flowers  arranged  as  are  the 
glumes,  lemmas,  paleas,  and  flowers  of 
a  grass  spikelet.  Fig.  7  is  a  diagram 
of  a  spikelet  for  comparison  with  Fig.  6.  [The  hy- 
pothetical flower-bearing  branchlet  is  never  elongate, 


12 


FIRST  BOOK  OF  GRASSES 


as  here  shown  for  the  sake  of  comparison.  The 
palea  is  immediately  above  the  lemma  and  the 
flower  immediately  above  the  palea.]  It  will  be  seen 
that  the  spikelet  is  theoretically  a  leafy  flowering 
branch  with  a  jointed  main  axis,  the  flowers,  except 


riRST  GLUME 


FIG.  6.  Diagram  of  a  flowering 
branch. 


FIG.  7.  Diagram  of 
spikelet. 


for  the  minute  lodicules,  reduced  to  the  essential 
organs.  In  Fig.  8  a  typical  grass  spikelet  is  shown, 
the  lemmas  and  paleas  nearly  closed  together  and 
concealing  the  flowers. 

The  spikelet  is  characteristic  of  grasses  and  is  not 
found  in  any  other  family  except  that  of  the  sedges. 


THE  GRASS  FAMILY 


13 


In  the  spikelets  of  sedges  the  florets  are  commonly, 
but  not  always,  spirally  arranged,  there  never  is  a 
palea,  and  the  fruit  is  an  achene  or  nutlet.     [The 
" seeds"  of  buttercups  and 
mints  are  achenes  or  nut- 
lets.] 

In  grasses  specialization 
takes  place  mostly  in  the 
spikelet.  By  its  vegetative 
characters  we  know  a  given 
plant  to  be  a  grass,  but  it 
is  by  its  spikelets  and  their 
arrangement  that  we  know 
what  kind  of  a  grass  it  is. 
The  genera  of  grasses  and 
the  groups  of  genera  called 
tribes  are  based  on  the 
structure  of  the  spikelets 
and  their  arrangement  in 
the  inflorescence. 

Before  studying  the  spike- 
let  we  must  observe  the 
relatively  few  specializations  of  the  vegetative  parts. 
As  hi  other  plants,  stems  or  parts  of  stems  may  be 
underground.  These  underground  stems  (rhizomes, 
or  rootstocks)  are  borne  at  the  base  of  the  main  culm 
under  the  earth,  spread  out  horizontally,  and  in  due 
time  send  up  shoots  which  form  young  plants  at  a 
distance  from  the  parent.  Sod-forming  grasses  have 
this  kind  of  underground  stem.  Kentucky  blue- 


r/RST 

•LUME 


FIG.  8.  Generalized  spikelet. 


14  FIRST  BOOK  OF  GRASSES 

grass  (Poa  pratensis,  Fig.  9)  furnishes  an  excellent 
example.  Sometimes  the  rhizome  is  thick  and  woody, 
sending  up  shoots  from  its  nodes,  the  whole  forming  a 
dense  colony,  as  in  gama-grass  (Tripsacum  dacty- 
loides).  A  rhizome,  being  a  stem,  is  jointed  and 
bears  scales,  which  are  reduced  leaves.  By  these  it 
may  always  be  distinguished  from  a  root,  which 
is  not  jointed  and  never  bears  scales.  In  some 

grasses  the  shoots 
borne  at  the  base 
of  the  culm  are 
on  the  surface  of 
the  earth  instead 
of  beneath  it. 
Such  shoots  are 
stolons,  or  run- 
ners. These,  like 
rhizomes,  are 

FIG.  9.  Base  of  plant  and  underground  parts,    jointed    and    bear 
roots  and  rhizomes,  of  Poa  pratensis. 

scales  or,  some- 
times, well-developed  leaves.  Rhizomes  and  stolons 
both  bear  roots  at  the  under  side  of  the  nodes.  In  a 
few  species,  Bermuda-grass  for  one,  a  plant  may 
produce  either  rhizomes  or  stolons  according  to  the 
conditions  under  which  it  is  growing.  There  is  no 
real  difference  between  a  rhizome  and  a  stolon,  the 
one  is  below  ground  and  colorless,  the  other  above 
ground  and  green. 

Culms  are  hollow  in  most  grasses,  but  in  corn, 
sugar-cane,  sorghum,  and  related  grasses  they  are 


THE  GRASS  FAMILY  15 

pithy.  They  may  be  erect,  spreading,  or  creeping; 
they  may  be  simple  or  freely  branching.  A  branch 
is  borne  only  at  a  node  in  the  axil  of  a  sheath,  that  is, 
between  the  sheath  and  the  culm.  It  either  grows  up 
parallel  with  the  parent  culm  until  it  emerges  from 
the  sheath  or  the  young  branch  splits  the  sheath  and 
grows  outward.  In  manuals  of  botany  these  two 
methods  of  branching  are  called  intravaginal,  that 
is,  inside  the  vagina  (Latin  for  sheath),  and  ex- 
travaginal,  outside  the  sheath.  In  bunch-grasses, 
like  orchard-grass  and  the  wheat-grasses  of  the 
West,  the  branching  is  intravaginal;  in  Kentucky 
blue-grass,  quack-grass,  and  others  producing  rhi- 
zomes or  stolons,  the  branching  is  extravaginal. 
The  branches  borne  at  the  middle  and  upper  nodes 
of  a  culm  are  nearly  always  intravaginal.  If  they 
spread  from  the  parent  culm  they  do  not  burst 
through  the  sheath  but  carry  it  with  them. 

Leaves  are  always  borne  at  the  nodes  and  are 
always  2-ranked  (see  Fig.  1,  page  9).  In  corn  and 
other  large  grasses  the  leaves  sometimes  appear 
to  be  all  on  one  side  instead  of  2-ranked.  This  is 
due  to  a  twisting  of  the  culm  inside  the  sheath. 
Sometimes  in  large  grasses,  particularly  in  sugar- 
cane and  in  bamboos,  the  leaves  fall,  leaving  the  culm 
naked.  In  relatively  few  grasses  the  edges  of  the 
sheath  are  grown  together,  forming  a  tube.  Some- 
times the  blade  of  the  leaf  is  not  developed.  This  is 
always  the  case  in  the  leaves  or  scales  of  rhizomes 
(Fig.  9),  and  often  in  those  of  stolons  and  in  the 


16  FIRST  BOOK  OF  GRASSES 

lowermost  leaves  of  a  culm,  especially  in  bamboos. 
Blades  may  be  flat  or  folded  (often  called  con- 
duplicate)  or  involute;  that  is,  rolled  lengthwise. 
Rarely  the  inrolled  edges  are  grown  together,  so 
that  the  blade  really  has  no  upper  surface.  Such 
leaves  are  called  terete  (meaning  rounded).  Blades 
vary  greatly  in  size,  shape,  and  texture,  smoothness 
or  hairiness.  In  broad  leaves  there  is  sometimes  a 
narrow  neck,  or  petiole  (leaf -stalk),  between  the 
sheath  and  the  blade. 

SUMMARY 

Grasses  are  distinguished  by  jointed,  round  or 
flattened,  usually  hollow,  culms,  with  solid  nodes; 
2-ranked  leaves,  composed  of  sheath  and  blade, 
with  a  ligule  at  their  junction;  and  by  the  spikelets 
with  2-ranked  glumes  and  florets. 

REVIEW 

(1)  How  is  a  grass  distinguished  from  all  other  plants? 

(2)  Break  a  cornstalk  and  note  the  arrangement  of  the  torn 
fibers  standing  out  of  the  pith.    Compare  this  with  the  cut  end 
of  any  twig  of  a  tree  or  shrub.    Cut  across  a  wheat,  oat,  or  rye 
straw  and  compare  with  the  cornstalk  and  with  the  twig. 

(3)  Examine  the  culm  (nodes  and  internodes)  above  and  below 
ground  and  leaves  (sheath,  ligule,  and  blade)  of  any  available 


(4)  How  is  a  rhizome  distinguished  from  a  root? 

(5)  What  is  the  difference  between  a  rhizome  and  a  stolon? 


LESSON   II 
THE  SPIKELET  AND  THE  INFLORESCENCE 

THEORETICALLY  the  spikelet  is  a  reduced  leafy 
branch.  In  the  generalized  spikelet  shown  in  Fig.  8 
the  likeness  to  a  jointed  culm  with  2-ranked  leaves 
(Fig.  1)  is  readily  seen,  the  glumes  and  lemmas  corre- 
sponding to  sheaths,  their  blades  not  developed.  The 
palea,  with  two  nerves  and  with  its  back  to  the  axis, 
corresponds  to  a  minute  bract  (the  prophyllum) 
borne  at  the  base  of  a  branch  in  the  axil  of  a  sheath. 
The  prophyllum  is  always  2-nerved,  with  its  back 
(that  is,  the  space  between  the  nerves)  against  the 
main  axis  and  its  margins  clasping  the  young  branch. 
The  flower,  also,  is  theoretically  an  ultimate  branch- 
let.  In  the  flower-bearing  lemmas,  therefore,  the 
palea  is  developed,  while  in  the  glumes,  bearing  no 
flowers,  there  are  no  paleas.  Glumes  and  lemmas 
are,  morphologically,  reduced  leaves,  the  lower  pair, 
not  flower-bearing,  being  termed  glumes,  the  flower- 
bearing  ones  being  termed  lemmas.  (See  Fig.  7.) 

The  jointed  axis  of  the  spikelet  (the  rachilla) 
corresponds  to  the  jointed  culm  and,  like  it,  usually 
breaks  at  the  nodes,  the  internode  (the  part  of  the 
rachilla  between  two  nodes)  remaining  attached  to 
the  floret  at  its  base  (Fig.  4),  just  as  in  a  broken 
grass  stem  the  internode  of  the  culm  remains  with 

17 


18 


FIRST  BOOK  OF  GRASSES 


the  sheath  that  surrounds  it;  that  is,  the  break 
normally  comes  just  under  the  node.  Rachis 
(which  means  the  spine,  or  backbone)  and  axis 
(the  imaginary  central  line  of  any  body)  are 

often  used  inter- 
changeably as  bo- 
tanical terms.  In 
most  recent  works 
on  grasses  and  in 
these  lessons,  axis 
is  used  for  the 
main  axis  of  a  eom- 
pound  inflores- 
cence, rachis  for 
the  axis  or  sup- 
port of  the  spike- 
lets.  In  Fig.  10 
are  shown  the  axis 
of  a  panicle  .(A) 
and  the  rachis  of 

FIG.  10.  Forms  of  inflorescence:  A,  panicle;     a  raceme  (B)  '  the 
B,  raceme;  C,  spike.  Qf 


(C)    is  concealed  by  the  overlapping  spikelets. 

Spikelets  are  borne  pediceled  (that  is,  on  a  pedicel 
or  foot  stalk)  or  sessile  (without  a  pedicel)  in  leafless 
panicles,  racemes,  or  spikes  (Fig.  10)  .  These  different 
types  of  inflorescence  insensibly  grade  into  each 
other.  The  axis  and  branches  of  a  panicle  and  the 
rachis  of  a  raceme  or  spike  may  be  as  elaborately 
modified  and  specialized  as  may  be  the  parts  of  a 


THE  SPIKELET  AND  THE  INFLORESCENCE     19 

spikelet.  The  axis,  rachis,  or  branches  may  be 
continuous  (not  jointed),  or  articulate  (jointed)  and 
usually  disarticulating  (breaking  up).  The  break- 
ing up  takes  place  at  definite  points  and  has  to  do 
with  scattering  the  seed.  The  point  of  disarticula- 
tion  is  the  same  in  grasses  of  the  same  kind  (or 
genus)  and  is  usually  alike  in  related  genera,  and 
for  this  reason  is  of  great  importance  in  the  classifica- 
tion of  grasses.  When  there  are  no  joints  in  the  axis 
or  branches,  the  disarticulation  comes  in  the  spikelet, 
either  above  the  glumes  and  between  the  florets  or 
below  the  glumes.  Modifications  of  these  two  ways 
of  disarticulating  will  be  met  with  later.  The  study 
of  the  form  of  inflorescence  and  the  modification  of 
its  parts  will  be  carried  on  together  with  that  of  the 
spikelet. 

SUMMARY 

A  spikelet  consists  of  glumes  and  florets,  in  two 
ranks  and  alternate  on  the  rachilla,  the  florets  consist- 
ing of  lemma,  palea,  and  the  inclosed  flower.  Every 
organ  found  in  the  most  highly  specialized  spikelet 
is  to  be  interpreted  as  an  elaboration  or  a  reduction 
of  one  of  these  parts.  The  spikelet  is  the  unit  of  the 
inflorescence;  the  floret  is  the  unit  of  the  spikelet. 
The  spikelet  is  always  simple;  that  is,  the  rachilla 
never  branches.  The  floret  is  always  1 -flowered 
with  never  more  than  one  lemma  and  one  palea;  the 
glumes  and  florets  are  always  alternate,  two  consecu- 
tive ones  never  being  borne  one  above  the  other. 


20  FIRST  BOOK  OF  GRASSES 

These  basic  facts  kept  in  mind  will  aid  in  the  recogni- 
tion of  complicated  or  congested  spikelets  and  in  the 
correct  interpretation  of  their  parts. 

REVIEW 

(1)  Examine  a  spikelet  of  a  brome-grass,  such  as  cheat  or 
chess.    Separate  the  florets  from  each  other  and  from  the  glumes. 
Note  that  these  disjoint  without  tearing.    Open  out  the  lemma 
and  palea.    Note  that  these  permanently  adhere  at  their  base; 
that  they  can  only  be  torn  or  cut  apart. 

(2)  Name  the  parts  of  a  spikelet. 

(3)  What  is  their  arrangement? 

(4)  What  is  the  difference  between  a  rachis  and  a  rachilla? 


LESSON  III 
MODIFICATIONS  OF  THE  SPIKELET 

TAKING  the  generalized  spikelet  as  a  beginning, 
examine  Figs.  4  and  8.  Note  that  the  glumes  and 
lemmas  have  nerves  or  veins  (fibre-vascular  bundles) 
running  from  the  base  to  the  apex  or  nearly  to  it, 
one  nerve  in  the  middle  and  an  equal  number  on 
each  side,  there  being  an  odd  number  of  nerves  in 
the  glumes  and  lemmas.  In  the  palea  there  are  only 
two  nerves;  none  in  the  middle.  The  modifications 
and  variations  of  spikelets  will  be  studied,  as  nearly 
as  possible,  in  the  order  of  their  increasing  com- 
plexity. No  attempt  should  be  made  to  fix  in  mind 
the  forms  of  specialization  here  enumerated.  This 
lesson  is  only  meant  to  put  one  on  the  lookout  for 
modifications,  so  that  one  may  be  prepared  to  recog- 
nize a  given  organ  under  various  guises. 

(1)  Spikelets  differ  in  size.     (Bromus  or  brome- 
grass,  meadow  fescue,  and  blue-grass  are  examples.) 

(2)  The  number  of  florets  may  be  reduced  to  one 
or  increased  to  twenty  or  more. 

(3)  The  parts  of  the  spikelet  vary  in  their  relative 
sizes.    The  glumes  may  be  large  and  the  florets  small 
or  the  florets  large  and  the  glumes  small. 

(4)  The  rachilla  joints  may  be  slender  or  thick,  so 
short  that  the  florets  appear  to  be  opposite,  or  nearly 

21 


22  FIRST  BOOK  OF  GRASSES 

as  long  as  the  florets  themselves;  the  node  at  the 
base  of  the  floret  (the  callus)  is  sometimes  prolonged 
into  a  sharp  point;  the  uppermost  rachilla  joint  may 
bear  no  floret  and  may  extend  into  a  little  bristle. 

(5)  The  glumes  may  vary  in  shape,  in  texture, 
and  in  the  number  of  their  nerves  and  may  be  gla- 
brous (smooth)  or  pubescent  (hairy) ;  sometimes  they 
are  reduced  to  rudiments  and  sometimes  they  are 
suppressed. 

(6)  The  lemma  is  subject  to  such  great  modifica- 
tions that  we  shall  now  note  only  the  simplest  ones. 
As  in  the  glumes,  the  shape  and  texture  and  the 
number  of  nerves  vary.    The  summit  of  the  lemma 
may  be  acute  (pointed)  or  acuminate  (long-pointed) 
or  obtuse  (blunt)  or  it  may  be  lobed  or  cleft.    The 
nerves  may  be  faint  or  strong,  or  may  extend  into 
awns  (bristles)  beyond  the  body  of  the  lemma.    The 
lemma  is  sometimes  minute,  but  it  is  never  sup- 
pressed. 

(7)  The  palea  is  always  2-nerved,  but  in  a  few 
grasses  the  nerves  are  so  close  together  as  to  appear 
like  a  single  one.    In  others  they  are  far  apart  and 
the  palea  may  split  between  them.    The  palea  differs 
in  size  and  texture.    In  a  few  genera  it  is  reduced  or 
even  suppressed. 

(8)  Spikelets  are  compressed  (flattened)  laterally 
(sidewise),  as  in  Figs.   11-14,  or  dorsally  (on  the 
back),  as  in  Figs.  60-66.     The  side  or  back  of  a 
spikelet  is  recognized  from  the  position  of  the  florets 
on  the  rachilla.    The  palea  side  of  the  floret  is  always 


MODIFICATIONS  OF  THE  SPIKELET  23 

toward  the  rachilla.  Taking  this  as  the  " front" 
of  a  floret,  the  back  (or  dorsum)  is  the  back  of  the 
lemma.  Spikelets  with  many  florets,  or  those  in 
which  the  glumes  or  lemmas  are  folded  on  the  mid- 
nerve,  are  generally  laterally  compressed;  those  with  a 
single  fertile  floret  and  with  convex  (rounded)  glumes 
and  lemma  are  generally  dor  sally  compressed. 

(9)  Spikelets  are  sometimes  unisexual  (of  one  sex) 
instead  of  perfect  (having  both  stamens  and  pistil). 
The  two  kinds,  pistillate  (the  ovule-producing)  and 
staminate    (pollen-producing)   may  be  borne  on  a 
single  plant,  as  in  corn,  with  pistillate  spikelets  in  the 
ear  and  staminate  spikelets  in  the  tassel,  or  in  differ- 
ent plants,  as  in  salt-grass  and  buffalo-grass.    Grasses 
with  staminate  and  pistillate  spikelets  on  the  same 
plants  are  monoecious  (which  means  dwelling  in  one 
house) ;  those  with  staminate  and  pistillate  spikelets 
on  different  plants  are  dioecious  (dwelling  in  two 
houses).    The  unisexual  spikelets  of  a  single  species 
may  be  similar  in  appearance,  or  they  may  be  very 
unlike,  as  in  corn. 

(10)  Some  grasses  with  perfect  spikelets  bear  in 
addition  staminate  spikelets  or  neuter  spikelets  (hav- 
ing neither  stamens  nor  pistils).     These  additional 
spikelets  may  be  similar  in  appearance  to  the  perfect 
ones  or  very  unlike  them.    They  are  borne  in  the 
same  inflorescence  as  the  perfect  spikelets  and  are 
usually  paired  with  them. 

(11)  The  florets  of  a  single  spikelet  may  be  of  two 
kinds,  perfect  and  sterile,  the  sterile  being  either 


24  FIRST  BOOK  OF  GRASSES 

staminate  or  neuter.  In  spikelets  like  those  of  Figs. 
11-14,  with  several  to  many  florets,  the  uppermost 
florets  are  commonly  sterile  (not  perfecting  seed), 
though  they  are  like  the  fertile  florets  in  appearance 
and  have  rudimentary  stamens  and  pistils.  In  some 
grasses  the  sterile  florets  are  very  different  from  the 
fertile  ones  and  may  be  borne  above  or  below  them 
on  the  rachilla.  The  position  of  sterile  florets  in  the 
spikelet  is  the  same  in  large  series  of  related  grasses; 
hence  it  is  of  great  importance  in  classifying  genera. 
The  type  of  modification  of  the  sterile  floret  is  also 
uniform  within  a  genus,  and  generally  in  related 
genera.  It  commonly  consists  of  a  lemma  without  a 
palea,  but  there  may  be  a  rudimentary  or  even  a 
well-developed  palea. 

These  types  of  modification  will  be  brought  out 
and  illustrated  in  the  succeeding  lessons. 

SUMMARY 

All  spikelets  are  built  on  the  simple  plan  of  2- 
ranked  florets  with  a  pair  of  glumes  at  the  base. 
The  spikelet  as  a  whole  and  each  of  its  organs  is 
subject  to  modification.  The  palea  and  one  or  both 
glumes  may  be  suppressed;  the  lemma  may  be  re- 
duced but  is  never  suppressed.  The  position  and 
type  of  modification  of  sterile  florets  are  of  impor- 
tance in  classification. 

The  parts  of  a  spikelet,  however  complex,  are 
recognizable  as  rachilla,  glumes,  lemma,  or  palea. 


LESSON  IV 

PEDICELED  SPIKELETS  OF  FEW  TO  MANY 
FLORETS 

TAKING  the  spikelet  of  cheat  or  chess  (Bromus 
secalinus),  Fig.  11,  as  a  starting  point,  we  have 
one  but  little  different  from  the 
diagrammatic  spikelet  (Fig.  8). 
[Names  incidentally  mentioned 
should  not  be  memorized.]  The 
lemmas  are  convex  on  the  back, 
several -nerved,  2-toothed  at  the 
apex  and  bear  an  awn  from  be- 
tween the  teeth.  The  awn  is 
the  midnerve  extending  beyond 
the  body  of  the  lemma.  The 
rachilla  joints  are  short,  bring- 
ing the  florets  (Fig.  11,  B)  close 
together.  The  articulation  is 
above  the  glumes  and  between  FlG-  *L  A, 

.  ered  spikelet  of  Bromus 

the  florets.  The  palea  is  grown  secalinus;  B,  single 
fast  to  the  grain.  All  species  of  floret' 
Bromus  have  spikelets  of  this  character,  differing 
in  size,  texture,  length  of  the  awn,  which  may  be 
much  longer  or  reduced  to  a  mucro  (a  minute  point) 
or  even  suppressed,  in  being  glabrous,  as  in  cheat,  or 
pubescent.  The  pubescence  may  cover  the  lemma 

25 


26 


FIRST  BOOK  OF  GRASSES 


or  be  along  the  margins  only.  These  differences 
distinguish  the  species.  A  genus  is  composed  of  one 
to  many  species  having  few  to  several  important 
characters  in  common,  and  presumably  descended 
from  a  common  ancestor.  Groups  of  species  having 
less  important  characters  in  common  form  related 
genera.  Festuca  (Fig.  12)  is  related  to  Bromus, 
having  few  to  several-flowered 
spikelets,  disarticulating  above 
the  glumes  and  between  the 
florets  and  with  several-nerved 
lemmas;  but  the  lemmas  are 
awned  from  the  tip,  or  pointed 
only,  and  not  toothed,  and 
the  palea  is  not  grown  to  the 
grain. 

A  large  number  of  grasses 
have  laterally  compressed 
spikelets  of  this  general  type, 
disarticulating  above  the 

FIG.   12.   A,  spikelet  of  Fes- 

tuca  ovina;  B,  lemma  de-  glumes  and  between  the  tew 
tached-  to  many  florets.     They   are 

sorted  into  genera  and  the  genera  separated  from 
each  other  chiefly  according  to  the  modifications 
of  the  lemma.  In  Panicularia  (Fig.  13)  the  lemmas 
are  broad  and  obtuse  with  strong  parallel  nerves. 
In  Poa  (Fig.  14)  the  lemmas  are  keeled  on  the  back, 
and  have  five  nerves  converging  toward  the  acute 
but  never  awned  apex.  The  species  figured  (Ken- 
tucky blue-grass,  Poa  pratensis)  and  many  others 


PEDICELED  SPIKELETS  27 

are  villous  (having  soft  curly  hairs)  on  the  lower 
part  of  the  midnerve  and  the  marginal  nerves  and 
have  a  tuft  of  white  cottony  hairs  at  the 
base,  but  this  pubescence  is  not  found  in 
all  the  species. 

In  all  the  grasses  mentioned  so  far, 
the  spikelets  are  borne  in  panicles  (see 
Fig.  10,  A).  Spikelets  much 
like  those  of  Panicularia  (Fig. 
13)  but  borne  in  a  raceme 
and  having  awned  lemmas 
are  found  in  Pleuropogon 
(shown  in  Fig.  10,  B).  In 
these  spikelets  the  palea  is 
crested  or  winged  on  the  nerves 
(Fig.  15,  showing  a  three  quar-  FlG.  14.' 'Spike. 
ter  view  of  a  palea  removed  let  °.f  Poa 

x  tensis. 

from  the  floret). 

Returning   to   Fig.    11,   A,   we 
Sp!keiet30f  note  the  midnerve  of  the  lemma 
extending  as  an  awn  beyond  the 
minutely  toothed  apex.    The  mid- 
nerve  and  the  two  lateral  nerves 
as  well  are  extended  into  awns  in  Triodia 
flava  (Fig.  16,  the  floret  seen  from  the  back) ; 
the  apex  of  the  lemma  is  toothed  and  the 
nerves  are  villous  below.     In  Fig.  17  (floret  J 
of   Cottea  pappophoroides  opened  out  and™ 
seen  from  the  back)  the  lemma  is  lobed  and  nine  to 
eleven  of  its  many  nerves  are  extended  into  awns. 


28 


FIRST  BOOK  OF  GRASSES 


After  the  foregoing  the  spikelet  and  its  parts  will 
be  recognized  in  most  of  the  genera  of  the  group 
having  few  to  many-flow- 
ered pediceled  spikelets. 
As  stated  in  Lesson  III 
the  florets  in  a  single  spike- 
let  may  be  of  two  kinds. 
The  simplest  spikelet  of 
this  type  is  found  in  the 

FIG.    16.  i     /r>7 

Floret  of  reed   (Phragmites  commu- 

flava. 

floret  is  staminate  or  neu-  FIG.    17.  Lemma    of 
ter  and  its  lemma  is  much  longer  Cotiea  ^^horoides- 
than  in  the  other  florets  (Fig.  18,  A).     In  the  per- 
fect floret  (Fig.  18,  B)  it  will  be  seen  that  the  palea 
is  very  much  shorter  than  the  lemma,  that  the 


FIG.  18.  A,  spikelet  of  Phragmites  communis',  B,  floret. 

rachilla  bears  copious  long  soft  hairs,  and  that  in- 
stead of  disarticulating  at  its  summit  and  remaining 


PEDICELED  SPIKELETS 


29 


attached  to  the  floret  next  below,  it  disarticulates  at 
its  base,  remaining  as  a  tiny  feathery  stem  to  the 
floret  next  above,  its  copious  long  hairs  carrying  the 
floret  before  the  wind,  dispersing  the 
seed.  [The  hairs  are  much  more  co- 
pious than  shown  in  the  figure;  they 
are  slighted  to  avoid  obscuring  the 
difference  in  the  florets.] 

Another  spikelet  with  two  kinds  of 
florets  is  shown  in  Fig.  19  (Melica 
mutica).  In  this  the  lemmas  of  the  FlG- i»:  Spikelet  of 
upper  florets  are  reduced  in  size, 
changed  in  shape,  and  contain  no  flower.  Two  or 
three  of  them  are  crowded  together  in  a  little  club- 
shaped  body.  In  the  species  figured,  this  modifica- 
tion is  more  marked  than  in  most  of  the  species. 

In  Fig.  20  is  shown 
a  side  view  of  the 
florets  of  a  spikelet  of 
Pappophorum  vagina- 
turn,  the  glumes  re- 
moved. The  lowest 
floret  is  perfect.  Its 
broad  lemma  is  cut  into 
many  spreading  awns 
(compare  with  Fig.  17). 
The  two  to  four  other 
florets  are  crowded  on 
the  very  short  rachilla  and  are  sterile ;  their  lemmas 
are  similar  to  that  of  the  one  fertile  floret.  The 


FIG.  20.  Florets  of  Pappophorum 
vaginatum. 


30 


FIRST  BOOK  OF  GRASSES 


rachilla  does  not  disarticulate,  the  sterile  florets  re- 
maining permanently  attached  to  the  fertile  one,  the 
numerous  awns  of  all  together  forming  a  pappus-like 
crown  which  carries  the  seed  before  the  wind.  [Pap- 
pus is  the  "down"  on  the  seed  of  a  dandelion,  thistle, 
or  other  plant  of  their  family.] 

Next  we  shall  examine  the  inflorescence  of  a  grass 
having  spikelets  entirely  of  sterile  florets  in  addition 

to  spikelets  of  fer- 
tile florets.  Ex- 
amine Fig.  21,  A 
(Cynosurus  crista- 
tus),  which  shows 
a  small  part  of  a 
spike-like  panicle. 
The  spikelets  are 
borne  on  minute 

FIG.   21.   A,  part  of   a  panicle  of  Cynosurus    Pe^icels     On      Very 
cristatus;     B,    sterile    spikelet;     C,    fertile    short    Compound 

branches.    The 

lower  one  to  three  spikelets  of  each  little  branch 
are  sterile,  the  lemmas  containing  no  flowers  (Fig. 
21,  B).  The  upper  one  to  three  spikelets  are  smaller 
and  fertile  (Fig.  21,  C).  When  the  bracts  of  the 
sterile  spikelet  are  all  alike  empty,  why  are  all 
but  the  lower  pair  called  lemmas,  instead  of  glumes? 
In  many  cases  the  nature  of  modified  organs  can 
only  be  recognized  by  their  correspondence  to  or- 
gans in  the  same  relative  position  in  allied  but 
more  simple  forms.  In  all  the  spikelets  examined 


PEDICELED  SPIKELETS 


31 


so  far  (and  in  all  but  a  very  small  number  of 
grasses)  the  bracts  above  the  lower  pair  are  flower- 
bearing  or  have  a  palea,  which  indicates  their  struc- 
tural identity.  Corresponding  parts  in  a  modified 
spikelet  are,  therefore,  regarded  as  lemmas.  In  the 
grass  just  examined  the  sterile  spikelets  remain  on 
the  panicle  branches  after  the  fall  of  the  ripened 
fertile  florets  from  their  glumes. 

In  Fig.  22,  A  (Achy r odes 
aureum),  is  shown  a  fascicle 
of  one  fertile  and  three 
sterile  spikelets  of  another 
grass.  In  this  the  fascicles 
hang  from  the  short  slen- 
der branches  of  a  narrow 
panicle  and  disarticulate 
from  them,  falling  entire. 
This  is  the  first  example  we 
have  had  so  far  of  disartic- 
ulating branches  of  the  in- 
florescence. In  the  figure 
the  fascicle  is  seen  from  the 
inner  face  to  show  the  fer- 
tile spikelet,  which  from 
the  outside  is  nearly  hid- 
den by  the  sterile  ones.  Fig.  22,  B,  shows  a  sepa- 
rate fertile  spikelet.  It  will  be  seen  that  except 
for  the  glumes,  the  two  forms  are  strikingly  dif- 
ferent. The  fertile  spikelet  is  reduced  to  one 
fertile  and  one  rudimentary  floret,  both  awned, 


FIG.  22.  A,  fascicle  of  three  sterile 
and  one  fertile  spikelet  of 
Achyrodes  aureum;  B,  fertile 
spikelet. 


32 


FIRST  BOOK  OF  GRASSES 


while  the  sterile  spikelets  are  many-flowered  and 

awnless. 
We  shall  next  examine  a  grass  having  unisexual 

spikelets  (see  Lesson  III,  page  23),  the  two  forms 
borne  on  different  plants  (dioecious). 
(In  the  group  with  relatively  simple 
spikelets  which  we  are  now  studying 
there  are  no  monoecious  grasses). 
In  Fig.  23  are  shown  the  pistillate 
and  staminate  spikelets  of  salt-grass 
(Distichlis  spicata).  They  differ  but 
little  in  appearance  and  are  both 


FIG.  23.  Pistillate 
and  staminate 
spikelets  of  Dis- 
tichlis spicata. 

borne  in  narrow 
panicles.  [9  sig- 
nifies female,  d* 
male.  These  signs 
are  commonly 
used  to  indicate 
pistillate  and  sta- 
minate plants, 
respectively.] 

In  Fig.  24  are 
seen  the  strikingly 
diverse  staminate 
and  pistillate  spikelets  of  another  dioecious  species 


Fig.  24.    Staminate  and  pistillate  spikelets  of 
Scleropogon  brevifolius. 


PEDICELED  SPIKELETS  33 

(Scleropogon  brevifolius).  The  lemmas  of  the  stam- 
inate  spikelet  are  merely  pointed;  those  of  the 
pistillate  spikelet  bear  three  long  slender  twisted 
spreading  awns.  The  pistillate  florets  fall  from  the 
glumes  as  a  whole  (the  rachilla  not  disarticulating 
between  them)  and  roll  before  the  wind  as  tiny 
tumble  weeds. 

SUMMARY 

The  inflorescence  and  the  two  to  several-flowered 
spikelets  of  the  brome-grasses,  blue-grasses  and  their 
relatives  are  comparatively  simple.  In  a  few  genera 
sterile  spikelets  are  developed  and  in  a  few  others 
the  spikelets  are  unisexual. 

REVIEW 

Collect  specimens  of  orchard-grass,  meadow  fescue,  any 
species  of  brome-grass,  or  of  Poa,  or  of  any  available  grasses 
having  laterally  compressed,  few  to  several-flowered  spikelets. 
Identify  the  different  parts  of  the  spikelets.  Lemmas  may  be 
spread  out  for  examination  by  cutting  off  the  very  base  with  a 
sharp  knife  or  scalpel.  Spikelets  of  tough  or  rigid  texture  if 
soaked  in  water  for  a  few  minutes  may  be  dissected  without 
tearing.  If  very  tough  or  hard,  boiling  the  spikelets  in  water 
with  a  little  glycerine  (a  drop  of  glycerine  to  about  a  teaspoonful 
of  water)  will  make  them  manageable  and  keep  them  from  drying 
out  during  dissection. 


LESSON  V 


SESSILE  SPIKELETS  IN  TWO-SIDED  SPIKES 


RETURNING 


FIG.  25.  A,  part  of  a 
spike  of  Agropy- 
ron  repens',  B, 
part  of  rachis 
seen  from  the 
edge,  all  but 
two  spikelets  re- 
moved. 


again  to  the  spikelet  of  Bromus 
secalinus  (Fig.  11),  we  shall  strike 
out  in  another  direction.  Differ- 
entiation among  living  beings  does 
not  follow  a  line,  but  radiates  like 
waves  following  the  falling  of  a  peb- 
ble in  the  water,  or  rather  like  waves 
of  sound,  in  all  directions.  Hence  we 
can  not  follow  an  unbroken  line  in 
studying  the  increasing  complexity 
of  the  inflorescence  of  grasses.  We 
can  only  return  to  the  center  and 
start  out  on  another  line.  Compare 
Fig.  10,  A  and  B,  with  C,  and  with 
Fig.  25  (couch-grass  or  quack-grass, 
Agropyron  repens).  A  raceme  is  a 
panicle  reduced  to  its  lowest  terms. 
Eliminating  the  pedicels  of  the  spike- 
lets  of  a  raceme  we  have  a  spike,  the 
spikelets  set  directly  upon  the  rachis. 
In  such  an  inflorescence  the  rachis 
is  usually  more  or  less  thickened.  In 
Fig.  25,  A,  part  of  a  spike  is  shown 
from  the  flat  side  of  the  spikelet. 
The  rachis  is  jointed  and  a  spikelet  is 
34 


SESSILE  SPIKELETS  IN  TWO-SIDED  SPIKES     35 


borne  at  each  joint,  alternating  on  opposite  sides. 
The  rachis  is  thickened  and  the  joints  slightly  hol- 
lowed on  alternate  sides.  (See  Fig.  25,  B,  a  diagram- 
matic illustration  of  the  rachis  seen  from  the  edge 
with  all  but  two  spikelets  removed.) 

The  spikelet  is  not  very  different  from  that  of 
Bromus  (Fig.  11)  and  as 
in    that,    the    ripened 
florets    fall    from    the 
glumes. 

In  the  group  of 
grasses  taken  up  in  this 
lesson  the  specialization 
is  mostly  in  the  rachis 
and  in  the  position  of 
the  relatively  simple 
spikelets. 

In  Fig.  26,  a  spikelet 
of  cultivated  w  h  e  a  t 
(Triticum  cestivum),  we 
have  the  same  type  of 
spikelet  as  in  Fig.  25  but  with  fewer  and  much 
plumper  florets,  with  broader  lemmas  slightly  toothed 
at  the  apex,  and  with  long  awns  that  are  scabrous 
(rough,  like  a  file).  [Awns  form  the  " beard"  of 
wheat.]  The  spikelets  are  borne  on  a  jointed  rachis 
as  in  Fig.  25  (Agropyron  repens)  but  the  joints  are 
shorter,  bringing  the  spikelets  closer  together  and 
hiding  the  rachis.  In  this,  cultivated  wheat,  the 
florets  do  not  readily  fall  from  the  glumes  but  re- 


FIG.  26.  Spikelet  of  Triticum  cestivum. 


36  FIRST  BOOK  OF  GRASSES 

main  in  the  spike  and  the  ripened  grain  is  thrashed 
from  them.  This  persistence  of  the  lemma  and 
palea  has  been  fixed  by  selection  in  cultivation.  In 
the  closely  related  emmer  (Triticum  dicoccum)  the 
rachis  breaks  at  the  joints,  each 
joint  remaining  attached  to  its 
spikelet. 

Compare  Fig.  27  (Lolium  multi- 
florum)  with  Fig.  25.  Note  that  in 
Fig.  25  the  spikelets  are  borne 
flat  side  against  the  rachis,  while 
in  Fig.  27  they  stand  with  their 
edges  against  the  rachis.  The 
rachis  itself  is  of  the  same  type  as 
that  in  Fig.  25.  The  diagram- 
matic rachis  with  two  spikelets 
seen  edgewise  (Fig.  25,  B)  is  shown 
from  the  same  position  as  is  Fig. 
27.  In  this,  as  in  Agropyron,  the 
rachis  is  continuous  (not  disartic- 
ulating) and  the  florets  fall.  If 
FIG  27.  Part  of  a  spike  we  separate  a  spikelet  from  the 

of  Lohum  multiflorum.  *  r 

rachis  we  find  that  the  first  glume 
(the  one  that  would  be  against  the  rachis)  is  sup- 
pressed, the  first  floret  lying  directly  against  the 
rachis.  In  the  single  spikelet  borne  at  the  summit 
of  the  rachis  the  first  glume  is  developed  and  it 
about  as  large  as  the  second.  When  but  one  glume 
is  present,  we  know  which  glume  it  is  and  which  is 
suppressed  by  the  position  of  the  first  floret,  which 


SESSILE  SPIKELETS  IN  TWO-SIDED  SPIKES    37 


is  always  above  the  first  glume. 
When  no  glume  is  found  below  the 
first  floret,  it  is  obvious  that  it  is  the 
first  glume  which  is  suppressed. 

In  Fig.  28  (Lepturus  cylindri- 
cus)  we  have  a  greatly  thickened, 
strongly  nerved  rachis  with  spike- 
lets  placed  as  in  Fig.  27  but  reduced 
to  the  second  glume  and  a  single 
floret.  This  little  spikelet  is  sunken 
in  the  hollow  of  the  rachis  joint, 
the  second  glume  fitting  snugly 
over  the  hollow,  the  whole  forming 
a  long,  slender,  wiry  cylinder.  At 
maturity  the  rachis  disarticulates 
with  the  spikelets  firmly  embedded 
in  the  joints.  (See  diagram  of 
rachis,  Fig.  28,  B,  and,  -above,  a 
joint  with  spikelet  removed,  show- 
ing the  hollow,  and  a  second  with 
the  spikelet  in  position.)  The  plant 
bearing  these  spikes  grows  along 
mud  flats  near  the  sea.  The  rachis  , 

.  .  FIG.   28.   A,    part    of 

joints  are   cylindrical  and  readily      spike  of  Lepturus 

roll  down  the  slope  to  the  water.      %£*%'B^r 

Being  corky,  they  are  carried  by 

the  lightest  ripples  and  are  thus 

spread  over  wide  areas.    The  grain 

germinates  within  its  little  cell,  and  the  young  roots 

and  leaves  push  aside  the  water-soaked  glume. 


spikelets  removed; 
above,  diagram  of 
single  joint. 


38 


FIRST  BOOK  OF  GRASSES 


Returning  to  Fig.  25  with  its  one  spikelet  at 
each  joint,  flat  against  the  rachis,  compare  with  it 

Fig.  29  (Elymus  vir- 
ginicus,  or  rye-grass). 
In  this  there  are  two 
spikelets  at  each  joint 
of  the  rachis,  the  first 
glumes  back  to  back, 
the  spikelets  somewhat 
distorted,  each  pair 
reaching  around  the 
edges  of  the  rachis.  The 
figure  shows  a  pair  of 
spikelets  and  two  joints 
of  the  rachis,  with  the 
pair  of  spikelets  next 
above,  on  the  opposite 
side  of  the  rachis,  lightly 
sketched  in  behind;  two 
more  internodes  of  the 
rachis,  with  spikelets  re- 
moved, are  shown  by 
dotted  lines.  A  dia- 
grammatic sketch  of  a 
pair  of  spikelets,  the  dis- 
tortion reduced,  is  shown 

FIG.  29.  A,  pair  of  spikelets  of  Ely-  .  „ 

mua    virginicus;    B,  diagrammatic    aDOVe.     A  Comparison  OI 

figure  of  the  pair  of  spikelets.  the  diagrammatic  spike- 
let  with  the  spikelet  in  Fig.  25  will  show  the  structural 
similarity.  In  their  natural  position  the  spikelets, 


SESSILE  SPIKELETS  IN  TWO-SIDED  SPIKES     39 

overlapping  on  the  short  joints  and  extending  around 
the  edges  of  the  rachis,  so  that  at  least  one  is  seen 
nearly  edge-wise,  form  a  spike  that  may  well  be  con- 
fusing to  the  beginner,  especially  when,  as  in  the 
species  shown  in  Fig.  29  and  several  others,  the  glumes 
stand  out  like  a  4-rayed  involucre  below  the  ap- 
pressed  florets.  However,  a  single  joint  with  its 
spikelets  attached  cut  out  of  the  spike  readily  dis- 
closes the  structure.  In  some  species  of  Elymus 
there  are  three  spikelets  and  occasionally  four  or 
five  at  a  node,  the  distortion  being  correspondingly 
greater.  In  several  species  the  glumes  are  so  narrow 
as  to  appear  like  bristles  or  awns  only.  In  most  of 
the  species  the  rachis  is  continuous  and  can  not  be 
disjointed.  In  a  closely  related  genus,  Sitanion,  the 
rachis  disarticulates  at  the  base  of  each  joint,  the 
slender  rigid  joint  remaining  as  a  tiny  sharp-pointed 
stem  below  the  cluster  of  long-awned  spikelets.  The 
awn-like  glumes  of  Sitanion  commonly  split  between 
the  nerves,  sometimes  to  the  very  base,  appearing 
like  a  cluster  of  awns  below  the  florets. 

In  Elymus  and  Sitanion  the  spikelets  are  all  alike 
(or  some  occasionally  variously  aborted)  and  all 
sessile  (set  directly  on  the  rachis).  In  Fig.  30  (Hor- 
deum  nodosum,  one  of  the  wild  barleys),  a  group  of 
three  spikelets  and  a  joint  of  the  rachis  are  shown. 
As  in  Sitanion  the  rachis  disarticulates  at  the  base 
of  the  internode,  the  joint  remaining  attached  to  the 
spikelets  above  it.  Note  that  the  central  spikelet  is 
sessile  and  the  lateral  ones  pediceled,  that  the  lower 


40 


FIRST  BOOK  OF  GRASSES 


floret  of  the  central  spikelet  is  well  developed  while 
those  of  the  lateral  florets  are  rudimentary,  and  that 
the  back  of  the  floret  is  turned  from  the  rachis  with 
the  glumes  (bristle-like  in  this  species)  at  the  sides 
or  back,  contrary  to  the  arrangement  characteristic 

of  grass  spikelets.  The 
problem  of  the  glumes 
in  Hordeum  has  not 
been  satisfactorily 
solved.  It  appears  prob- 
able that  the  reduced 
rachilla  joint  between 
the  second  glume  and 
the  floret  is  twisted 
and  bent  inward,  bring- 
ing the  glumes  at  the 
side  or  back  of  the 
floret.  In  the  culti- 
vated barley  the  rachis 
does  not  break  up,  as 
in  the  wild  species,  the 
continuous  rachis  having  been  fixed  by  selection. 
The  florets  fall  from  the  spike  in  thrashing,  or  in 
naked  or  hull-less  barley  the  grains  fall  from  the 
lemma  and  palea,  as  in  wheat.  In  cultivated  2-rowed 
barley  the  lateral  spikelets  are  pediceled  and  sterile, 
as  in  the  wild  species,  but  in  4-rowed  and  6-rowed 
barley  the  lateral  spikelets  are  sessile  and  fertile, 
characters  fixed  by  selection. 

The    grasses    characterized    by    the "  spicate    in- 


FIG.  30.  Joint  of  spike  of  Hcrdeum 
nodosum. 


SESSILE  SPIKELETS  IN  TWO-SIDED  SPIKES     41 

florescence  dealt  with  in  this  lesson  form  the  barley 
tribe,  which  from  the  standpoint  of  man  is  the  most 
important  group  of  grasses,  if  not  of  all  plants,  in  the 
world,  containing  wheat,  barley,  and  rye. 

SUMMARY 

The  specialization  in  spicate  inflorescence  is  chiefly 
in  the  rachis  and  next  in  the  position  of  the  relatively 
simple  spikelets. 

When  the  glumes  are  distorted,  standing  side  by 
side,  as  often  found  in  species  of  Elymus,  or  when 
one  of  them  is  suppressed,  we  can  tell  which  is  which 
from  the  fact  that  the  first,  or  lowermost,  floret  is 
always  above  or  on  the  same  side  of  the  spikelet  as 
the  first  glume. 

REVIEW 

Collect  heads  of  wheat,  rye,  barley,  quack-grass,  species  of 
Elymus,  Lolium,  or  squirrel-tail  grass  (one  or  more  of  these  will 
be  found  anywhere  in  the  United  States).  Note  whether  the 
rachis  readily  disjoints.  If  so,  separate  out  a  single  joint  with 
the  spikelets  attached.  Note  where  the  rachis  breaks,  at  the 
summit  or  base  of  the  joint;  note  the  number  of  spikelets  at  a 
joint  and  the  number  of  florets  to  a  spikelet.  Distinguish  the 
individual  spikelets  and  their  parts.  If  the  rachis  does  not  dis- 
joint, cut  across  the  middle  of  the  internodes,  taking  out  a  single 
joint  with  attached  spikelets.  Note  the  number  of  spikelets  to  a 
joint;  whether  there  are  one  or  two  to  several  fertile  florets  to  the 
spikelet  and  whether  the  spikelet  is  placed  flatwise  or  edgewise 
to  the  rachis. 

Note  how  spikes  bearing  spikelets  with  scabrous  awns  push 
themselves  forward  when  handled. 


LESSON  VI 


PEDICELED  SPIKELETS  WITH  LARGE  GLUMES 
AND  OTHER  MODIFICATIONS 

TURNING  again  to  the  spikelet  of  Bromus  secalinus 
(Fig.    11),    compare  with    it   Fig.    31    (wild   oats, 

Avenafatua).  The 
glumes  are  greatly 
enlarged  and  the 
rachilla  joints  are 
so  short  that  the 
florets  appear  to 
be  almost  oppo- 
site. The  awn, 
instead  of  extend- 
ing from  the  apex 
of  the  lemma,  pro- 
trudes from  the 
back  and  is 
twisted  for  about 
half  its  length. 
We  noted  in  Les- 
son IV  that  the 
awn  is  an  exten- 
sion of  the  mid- 
nerve.  This  fact  is  well  shown  in  the  floret  of  wild 
oats  (Fig.  31,  B,  the  floret  seen  from  the  back),  in 

42 


FIG.  31.  A,  spikelet  of  Avenafatua;  B,  floret. 


PEDICELED  SPIKE  LETS  WITH  LARGE  GLUMES  43 

which  the  midnerve  leaves  the  body  of  the  lemma 
about  the  middle  of  its  back  and  becomes  a  free 
awn,  while  the  lemma  above  the  departure  of  the 
awn  is  nerveless.  This  is  invariably  the  case  when 


FIG.  32.  Spikelet  of  Trisetum 
spicatum. 

the  awn  is  dorsal  (that  is,  pro- 
truding from  the  back);  the 
lemma  is  always  nerveless 
above  it. 

Compare  Figs.  31  and  32 
(Trisetum  spicatum).  It  will 
be  seen  that  they  are  the  same 
type  of  spikelet.  In  Trisetum 
the  awn  is  loosely  twisted 
and  is  borne  nearer  the  apex 
of  the  lemma,  which  is  tipped 
with  two  slender  teeth. 

In  Danthonia  spicata  (Fig.  33)  the  florets  are  more 
numerous  and  are  smaller  in  proportion  to  the 
glumes.  The  broad  strongly  twisted  awn  arises  from 


FIG.  33.  Spikelet  of  Danthonia 
spicata;  floret  above. 


44 


FIRST  BOOK  OF  GRASSES 


between  the  teeth  or  lobes  of  a  bidentate  (2-toothed) 
apex  (see  floret  above,  seen  from  the  back). 

In  these  three  spikelets,  as  in  all  but  a  few  of  the 
grasses  of  the  oat  tribe,  the  florets  fall  from  the 
glumes  which  remain  on  the  pedicel.  In  velvet 
grass,  Notholcus  lanatus  (Fig. 
34),  the  spikelet  falls  entire. 
The  articulation  of  the  spikelet, 
taken  throughout  the  grass 
family,  is  so  nearly  uniform  for 
related  genera  that  it  is  relied 
on  to  differentiate  large  series. 
(See  Lesson  II,  on  inflorescence) . 
There  are  exceptions  to  the 
mode  of  articulation  character- 
istic of  the  group  as  a  whole 
in  the  case  of  a  few  genera  in 
three  of  our  tribes.  Such  exceptions  are  puzzling 
to  the  beginner,  leading  him  astray  in  using  keys. 
We  must  learn  to  observe  all  the  characters  of  the 
inflorescence  and  base  our  judgment  on  the  sum  total 
of  the  characters,  remembering  that  "  Nature  does 
as  she  pleases"  and  rejoicing  that  in  grasses  she  at 
least  pleases  to  keep  invariably  to  the  2-ranked 
arrangement  of  the  spikelets.  (See  the  summary  of 
Lesson  II).  In  Lesson  IV,  Figs.  18  and  19,  we 
observed  spikelets  in  which  the  florets  were  of  two 
kinds.  In  Notholcus  lanatus  the  lower  floret  is  per- 
fect and  awnless  and  the  upper  is  staminate  and 
bears  a  hook-like  awn  from  the  back  (Fig.  34,  B, 


FIG.  34.  A,  spikelet  of 
Notholeus  lanatus;  B, 
pair  of  florets. 


PEDICELED  SPIKELETS  WITH  LARGE  GLUMES   45 

florets  removed  from  the  glumes.    Note  the  curved 
and  exceptionally  long  lowermost  rachilla  joint.) 

In  Sphenopholis,  closely  related  to  Trisetum 
(Fig.  32) ,  the  spikelets  fall  entire,  as  in  velvet-grass. 
In  tall  oat-grass  (Arrhenatherum  elatius)  the  spikelets 
bear  one  perfect  awnless  floret  and  one  staminate 
awned  floret,  as  in  velvet-grass,  but  their  position  is 
reversed,  the  staminate  being  below  and  the  perfect 
above. 

SUMMARY 

In  the  oat  and  its  relatives  the  large  glumes  and 
the  awn  of  the  lemmas  are  the  most  prominent 
characters,  although  in  species  of  some  genera  the 
awn  is  wanting.  Pubescence  is  commonly  con- 
spicuous. The  inflorescence  is  an  open  or  contracted 
panicle. 

REVIEW 

Collect  panicles  of  wild  oats  or  awned  specimens  of  cultivated 
oats  (cultivated  oats  growing  wild  commonly  bear  awns),  of 
Danthonia,  one  or  more  species  of  which  are  to  be  found  through- 
out most  of  the  United  States,  and  any  of  the  related  grasses 
available,  and  examine  the  spikelets.  Place  a  floret  with  a 
twisted  awn  in  a  drop  of  water  and  observe  the  result.  In  awn- 
less  florets  of  cultivated  oats  note  that  the  midnerve  of  the  lemma, 
if  it  is  not  at  all  produced  into  an  awn,  stops  abruptly  at  the 
point  where  the  awn  would  arise  normally  and  that  the  lemma  is 
nerveless  above  this  point,  just  as  if  it  were  awned. 


LESSON  VII 


PEDICELED  ONE-FLOWERED  SPIKELETS 

TURN  to  the  spikelet  of  wild  oats  (Fig.  31)  and  in 
imagination  eliminate  all  but  the  lowest  floret  and 
the  glumes.  Better  still,  with  a  spikelet  of  oats  in 
hand  break  off  all  above  the  lowest  floret.  Now  we 
have  a  large  model  or  pattern  of  the  reduced  spikelet 
of  a  very  large  number  of  grasses,  red-top,  timothy, 
and  their  kind. 

Examine  Calamagrostis  canadensis  (Fig.  35,  the 
floret  raised  from  its  glumes)  and  note  how  it  corre- 
sponds to  the  pattern  obtained 
by  reducing  the  spikelet  of  oats 
to   a   single   floret.     The   only 
vestige  remaining  of  the  other 
florets   is    the   minute   rachilla 
joint  back  of  the  palea  (shown, 
exaggerated  somewhat,  in  Fig. 
35).    In  all  but  a  few  genera  the 
rachilla  is  entirely  suppressed. 
Compare  Fig.  35  with  Fig.  32 
and  note  that  Trisetum  reduced  to  a  single  floret 
would  closely  resemble  Calamagrostis. 

In  Agrostis  (Fig.  36)  the  rachilla  is  normally 
suppressed.  In  two  species  in  the  far  West  it  is 
present  as  a  minute  rudiment.  In  most  of  the  species 

46 


FIG.  35.  Spikelet  of  Cala- 
magrostis canadensis. 


PEDICELED  ONE-FLOWERED  SPIKELETS       47 

the  palea  also  is  suppressed  or  represented  by  a 
rudiment  only  (Fig.  36,  Agrostis  hiemalis,  the  floret 
with  palea  wanting,  raised  from  the 
glumes).  Here  we  have  specialization 
through  elimination,  the  spikelet  reduced 
almost  to  its  lowest  terms,  one  floret 
with  no  palea,  no  awn,  no  callus  hairs. 
In  this  particular  species  the  very  open 
panicles  break  off  and  roll  before  the 
wind  as  tumbleweeds,  scattering  the  FIG.  36.  Spike- 
seed.  Several  species  of  Agrostis  have  J?*  °f  Ag™s~ 

i  I  11  **  hiemahs. 

awned   lemmas   and  some  have  callus 
hairs,  shorter  and  less  copious  than  in  Calamagrostis. 
In  Sporobolus  (Fig.  37,  the  floret  raised  from  the 
glumes  and  containing  a  mature  grain) 
the    nerves    of    the    palea    are    wide 
apart   and   the   internerve    (the   space 
between  the  nerves)  is  thin  in  texture 
and  readily  splits  as  the  grain  matures. 
In  some  species  it  splits  to  the  apex, 
resulting  in  an  object    sorely  puzzling 
to  the  beginner,  the  two  halves  appear- 
ing like  two  1 -nerved  lemmas  or  paleas, 
in  addition  to  the  lemma  itself.    It  is 
FIG.  37.  spike-  in  such  cases  as  this  that  a  knowledge 
lot  of  sporo-  Of  the  structure  of  the  grass  spikelet  is 

bolus  airoides.  3 

necessary  for  the  correct  interpretation 
of  the  organs  observed.  In  this  genus  and  in  a  few 
others  the  pericarp  (meaning  around  the  fruit),  the 
wall  of  the  ripened  ovary  which  forms  a  covering 


48 


FIRST  BOOK  OF  GRASSES 


for  the  grain  and  is  usually  grown  fast  to  it,  is  free 
from  the  grain.  In  most  of  the  species  it  is  a  loose 
thin  sac,  which  readily  tears  when  moistened,  leav- 
ing the  grain  naked.  In  one  of  our  species  (Sporobo- 
lus  heterolepis)  the  pericarp  is  firm, 
like  a  thin  shell  about  the  grain. 

In  Cinna  the  two  nerves  of  the 
palea  are  so  close  together  that 
they  appear  to  be  a  single  nerve. 
In  one  of  the  species  this  nerve 
may  be  easily  split  into  two,  dem- 
onstrating the  derivation  of  the 
apparent  single  nerve. 

In  several  genera  the  glumes  are 
enlarged.  In  timothy  (Fig.  38) 
they  are  firm  in  texture,  strongly 
keeled,  and  abruptly  awned,  while 
the  lemma  is  much  smaller,  thin  in 
texture,  and  awnless.  The  spike- 
lets  are  so  congested  on  the  short 
branches  of  the  cylindrical  spike-like 
panicle  that  the  beginner  may  be 
puzzled  to  know  just  what  is  the 
unit  of  inflorescence.  Keeping  in 
mind  that  a  spikelet  never  is  com- 
pound, the  student  will  divide  and 
redivide  the  cluster  until  he  finds 
an  object  having  a  single  pair  of 
glumes  containing  the  floret.  FIG.  39.  Spikelet  of 

.  LA,.  <•  ,1         i  Alopecurus  gemcu- 

Another  modification  of  the  glumes     iatus. 


FIG.  38.  Spikelet  of 
Phleum  pratense; 
floret  above. 


PEDICELED  ONE-FLOWERED  SPIKELETS       49 

is  shown  in  Alopecurus  (Fig.  39).  The  margins  are 
grown  together  for  half  their  length.  As  in  Notholcus 
lanatus  (Fig.  34)  the  articulation  is  an  exception  to 
that  generally  characteristic  of  its  allied  genera,  the 
spikelets  falling  entire.  The  lemma  bears  a  delicate 
dorsal  awn  and  the  palea  is  suppressed.  In  most 
species  of  Alopecurus  the  panicle  is  as  dense  and 
spike-like  as  that  of  timothy. 

In  some  genera  the  glumes  are  reduced  (see  Fig. 
42),  and  in  a  few  species  the  first  glume  is  suppressed. 

In  Lesson  IV,  Fig.  21,  we 
noted  perfect  and  sterile 
spikelets  in  the  same  panicle 
and  in  Fig.  22  we  found  the 
spikelets  falling  in  clusters  of 
three  sterile  and  one  perfect 
spikelet.  In  Lycurus  (Fig.  40) 
the  spikelets  are  in  pairs  on 
the  ultimate  branchlets  of  the 
spike-like  panicle,  the  lower 
spikelet  sterile,  the  upper  per- 
fect. The  ultimate  branchlet 
itself  falls  with  the  spikelets  T 

.      ,  .  ,  FIG.    40.    Pair    of    spikelets, 

attached,      aS.     in      AchyrodeS        sterile   and   fertile    (spread 

(Fig.  22) .  Lycurus  shows  an-  apart)  of  Lycurus  Phleoides- 
other  peculiar  character  in  the  2-nerved  first  glume, 
one  lateral  nerve  being  undeveloped  or  very  faint. 
The  midnerve  is  extended  into  a  long  awn  and  the 
one  lateral  nerve  is  usually  extended  into  a  shorter 
awn,  but  is  sometimes  a  mere  tooth. 


50 


FIRST  BOOK  OF  GRASSES 


bergia  foliosa. 


The  glumes  and  lemma  in  the  spikelets  so 
far  examined  in  this  lesson  have  been  of  like 
texture,  membranaceous  (like  a  membrane  or 
skin). 

In  Muhlenbergia  (Figs.  41  and  42)  the  lemma  is 
firmer  in  texture  than  the 
glumes.  In  some  species 
of  the  genus  the  glumes 
are  much  reduced,  and  in 
some  they  are  well  devel- 
oped and  often  awned. 
The  lemmas  are  promi- 
4i.  spike-  nently  3-nerved  and  are 
awned  or  mucronate,  that 

,  .  ,  , 

is,  the  rmdnerve  extend- 
ing in  a  minute  point. 

In  four  of  our  genera  the  lemma  at 
maturity  is  firm  and 
hard  in  texture  and 
the  nerves  are 
scarcely  visible.  In 
Milium  (Fig.  43)  the 
lemma  is  rigid, 
smooth,  and  shining 
and  the  palea  is  of 

FIG.  43.    A,    spikelet 

of  Milium  effusum;  like  texture.    In  Ory- 
zopsis  (Fig.  44)  the 

lemma  bears  an  awn  that  readily  disarticulates 
at  its  base.  The  palea  is  nearly  inclosed  by  the 
lemma. 


FIG.  42.  A,  spike- 
let  of  Muhlen- 
bergia Schreberi; 
B,  bran  chief 
with  the  minute 
glumes  of  two 
spikelets  from 
which  florets 
have  fallen. 


PEDICELED  ONE-FLOWERED  SPIKELETS       51 


In  Stipa  (Fig.  45)  and  Aristida  (Fig.  46)  the  palea 
is  entirely  inclosed  in  the  lemma.     The  callus  (see 


FIG.  44.  A,  glumes, 
and  B,  floret  of  Ory- 
zopsis  racemosa. 


FIG.  45.  A,  glumes, 
and  B,  floret  of  Stipa 
spartea. 


FIG.  46.    Spikelet  of 
Aristida  dichotoma. 


page  22)  is  developed  into  a  needle-like  point  that 
readily  penetrates  clothing  or  works  its  way  into  the 
wool  of  sheep. 


52  FIRST  BOOK   OF  GRASSES 

In  Stipa  the  awn  is  composed  of  all  the  nerves  of 
the  lemma,  forming  a  solid  slightly  flattened  elongate 
body,  the  point  of  departure  from  the  body  of  the 
lemma  being  marked  by  an  abrupt  contraction  or  a 
ring  of  hairs.  In  some  species  the  lower  part  of  the 
awn  is  plumose  (covered  with  soft  fluffy  hairs,  like  a 
feather). 

In  Aristida  the  awn  is  divided  into  three;  that  is, 
the  three  nerves  at  first  unite,  then  separate.  The 
lemma  tapers  into  the  awn  with  no  visible  junction, 
as  in  Stipa.  Sometimes  the  undivided  part  of  the 
awn  is  elongate,  forming  a  slender  neck  and  some- 
times this  neck  is  twisted.  In  Aristida  dichotoma, 
the  species  shown  (Fig.  46),  the  lateral  awns  are  much 
shorter  than  the  central  one.  In  many  species  the 
three  are  subequal,  and  one  or  all  may  be  recurved  or 
loosely  twisted  at  the  base.  They  are  never  tightly 
twisted,  as  in  Stipa. 

SUMMARY 

The  specialization  in  this  group  of  grasses  con- 
sists in  the  reduction  of  the  relatively  simplified 
spikelet  to  a  single  floret.  In  most  of  the  genera  the 
spikelets  are  very  small.  The  glumes  may  be  re- 
duced to  rudiments  or  suppressed  or  may  be  well 
developed  and  somewhat  elaborated.  The  lemma 
may  be  delicate  or  indurate  (hardened)  and  may  be 
awned  from  the  back  or  the  summit.  The  palea 
shows  more  modification  in  this  group  than  in  any 
other.  It  may  be  suppressed  or  it  may  be  as  long  as 


PEDICELED  ONE-FLOWERED  SPIKELETS       53 

the  lemma ;  the  two  nerves  may  be  coherent,  appear- 
ing as  one,  or  widely  separated  with  the  delicate 
internerve  splitting.  The  rachilla  may  be  extended 
beyond  the  base  of  the  palea,  a  vestige  of  the  sup- 
pressed florets,  or  it  may  be  produced  into  a  sharp 
callus  below  the  lemma.  The  inflorescence  is  always 
a  panicle,  but  this  may  be  diffuse  or  dense  and 
cylindrical  or  capitate  (like  a  head). 

REVIEW 

Collect  panicles  of  redtop,  timothy,  or  of  any  grass  with 
laterally  compressed  1-flowered  spikelets.  If  the  inflorescence 
is  dense,  distinguish  the  individual  spikelets.  Dissect  the 
spikelets  and  note  whether  any  of  the  organs  are  suppressed. 
Note  the  point  of  attachment  of  the  awn,  if  any. 

If  possible,  collect  panicles  of  any  species  of  Stipa.  Lay  a 
few  of  the  florets  in  a  little  water  and  note  the  result.  Note  that 
twisted  awns  or  the  twisted  parts  of  an  awn  are  flattened. 


LESSON  VIII 
SESSILE  SPIKELETS  IN  ONE-SIDED  SPIKES 

As  stated  in  Lesson  V,  development  does  not  follow 
a  single  line,  so,  having  come  to  the  end  of  one  line, 
we  must  repeatedly  return  to  the  center  and  start  in 
a  new  direction.  In  the  group  of  grasses  taken  up 
in  this  lesson  the  principal  character  common  to 
all  is  the  spicate  inflorescence.  In  the  grasses  related 
to  barley  (Lesson  V)  we  found  solitary  2-sided  spikes, 
the  spikelets  sessile  on  opposite  sides  of  the  rachis. 
In  the  present  group  we  have  1 -sided  (unilateral) 
spikes,  the  spikelets  sessile  or  nearly  so  along  one 
side  of  the  rachis.  The  spikelets  themselves  range 
from  the  simple  one  of  yard-grass,  Eleusine  indica 
(Fig.  47),  to  highly  specialized  ones.  Compare 
Fig.  47,  A,  with  Figs.  11  and  14.  It  will  be  seen  that, 
although  the  glumes  and  lemmas  of  Eleusine  are 
strongly  keeled,  the  spikelets  are  of  the  same  type; 
but  these  spikelets  are  very  differently  arranged 
(Fig.  47,  B),  being  crowded  and  imbricate  (over- 
lapping like  shingles)  in  two  rows  on  one  side  of  the 
rachis.  Two  to  several  of  these  spikes  are  borne 
together,  digitate  or  nearly  so.  [Digitate  means 
arranged  like  fingers  (digits),  but  as  a  botanical 
term  it  indicates  an  arrangement  more  like  that 

54 


SESSILE  SPIKELETS  IN  ONE-SIDED  SPIKES     55 


FIG.  47.  A,  spikelet  of  Eleusine  indica;  B,  inflorescence. 

of  a  bird's  toes,  the  spikes  borne  on  so  short  an  axis 
that  they  appear  to  spring  from  the  same  point.] 

In  Lesson  VII  we 
obtained  the  pat- 
tern of  the  1 -flowered 
spikelet  by  eliminat- 
ing all  but  the  lowest 
floret  and  the  glumes 
from  a  several-flow- 
ered spikelet.  Elimi- 
nating all  but  the 
lowest  floret  of  Eleu- 
sine we  have  a  model 
of  the  spikelet  of  Bermuda-grass,  Capriola  Dactylon 
(Fig.  48,  A).  A  vestige  of  the  eliminated  florets  re- 


FIG.  48.  A,  spikelet  of  Capriola  Dactylon, 
floret  raised  above  the  glumes;  B,  in- 
florescence. 


56 


FIRST  BOOK  OF  GRASSES 


mains  in  the  prolonged  rachilla,  often  with  a  rudi- 
mentary floret  at  its  apex.  The  arrangement  of  the 
inflorescence  (Fig.  48,  B ;  three  of  the  spikes  indicated 
in  skeleton  only)  is  the  same  as  in  Eleusine. 


FIG.  49.  A,  spikelet  of  Chloris  latisquamea;  B, 
fertile  lemma  spread  out;  C,  sterile  lemma 
spread  out;  D,  inflorescence. 

Compare  Figs.  48  and  49  (Chloris  latisquamea). 
In  the  latter,  the  upper  florets  instead  of  being  sup- 
pressed are  developed  into  one  or  a  few  sterile  florets, 
consisting  of  modified  lemmas  without  paleas.  Turn 
to  Lesson  III  in  which  sterile  florets  are  discussed 


SESSILE  SPIKELETS  IN  ONE-SIDED  SPIKES        57 


(page  23).  In  Melica  (Fig.  19)  we  had  an  example 
of  such  sterile  florets,  and  in  Chloris  we  have  another. 
In  each  case,  the  sterile  lemmas  if  spread  out  show 
their  derivation  from  the  ordinary  fertile  lemmas. 

In  grama  grass,  Bouteloua 
(Figs.  50  and  51),  is  found 
the  greatest  specialization 
of  the  sterile  floret.  It 
is  often  more  prominent 
than  the  fertile  floret  and 
so  modified  that  its  deriva- 
tion is  not  always  obvious. 
The  pattern  of  its  lemma, 
however,  is  like  that  of 
the  fertile  one,  3-nerved, 
the  nerves  extending  into 
awns  (Figs.  50,  C  and  51,  C.) 
The  internerves  are  com- 
monly broadened  and  re- 
duced (as  in  Fig.  51,  C),  or 
even  suppressed.  There  is 
usually  a  single  such  floret, 
but  in  some  species  there  are  FIG.  50 
two,  or  even  three.  A  second 
sterile  lemma  when  present 
may  have  a  single  awn  or  be 
awnless,  or  even  nerveless  (Fig.  51,  D).  In  a  few 
species  the  sterile  floret  sometimes  incloses  a  palea 
and  stamens.  Note  that  in  Bouteloua  the  spikes  are 
not  digitate,  as  in  the  foregoing  genera,  but  are 


A,  spikelet  of  Boute- 
loua curtipendula;  B,  fertile 
lemma  spread  out;  C,  sterile 
lemma  spread  out;  D,  in- 
florescence. 


58 


FIRST  BOOK  OF  GRASSES 


racemose  (Figs.  50,  D,  and  51,  E);  that  is,  the  axis 
between  the  spikes  is  elongate  instead  of  greatly  re- 
duced. (In  Fig.  10,  B,  is  shown  a  raceme  of  spike- 
lets;  in  Bouteloua  we  have  a  raceme  of  spikes,  each 


FIG.  51.  A,  spikelet  of  Bouteloua  gracilis;  B,  fer- 
tile lemma  spread  out;  C,  first  sterile  lemma 
spread  out;  D,  second  steri'e  lemma  spread  out; 
E,  inflorescence. 

composed  of  few  to  many  sessile  spikelets.)  In  Boute- 
loua gracilis  (Fig.  51)  and  related  species  the  florets, 
as  is  usual  in  this  group,  fall  from  the  glumes,  these 
remaining  on  the  rachis.  In  B.  curtipendula  (Fig.  50) 
and  its  relatives,  the  entire  spike  falls  from  the 
main  axis, 


SESSILE  SPIKELETS  IN  ONE-SIDED  SPIKES      59 

In  an  allied  genus,  Cathestecum  (which  looks  like  a 
diminutive  Bouteloua)  with  but  one  species  in  the 
United  States,  the  spikes  consist  of  three  spikelets 
crowded  on  the  short  rachis,  the  uppermost  fertile, 
the  two  lower  staminate  or  neuter.  The  spikes  fall 
as  a  whole  from  the  axis. 

In  Lesson  III  (page  24)  it  is  stated  that  the  posi- 
tion of  sterile  florets  in  the  spikelets  is  the  same  in 
large  series  of  related  grasses.  In  the  spikelets  so  far 
studied  in  this  lesson  the  sterile  florets  are  above  the 
perfect  one.  There  is  a  single  exception  to  this  rule 
in  Campulosus,  in  which  the  two  lower  lemmas  are 
well  developed  but  empty,  the  third  fertile,  and  the 
upper  one  to  three  empty,  like  the  lower. 

In  two  genera  in  this  group,  Spartina  and  Beck- 
mannia,  the  spikelets  fall  entire.  (See  Lesson  VI, 
page  44,  on  exceptions).  In  Spartina  the  spikelets 
are  strictly  1-flowered;  in  Beckmannia  they  are 
usually  1-flowered,  but  sometimes  a  second  floret  is 
developed. 

Throughout  we  have  seen  widely  different  forms, 
such  as  Eleusine  and  Bouteloua,  connected  by  inter- 
mediate forms  like  Capriola  and  Chloris.  Such  an 
intermediate  between  pediceled  spikelets,  as  in 
Bromus,  Poa,  and  others  of  Lesson  IV,  and  sessile 
spikelets,  as  in  the  group  we  are  now  studying,  is 
found  in  Leptochloa,  in  which  the  spikelets  are  ar- 
ranged along  one  side  of  the  slender  rachises,  but  are 
borne  on  very  short  pedicels.  The  spikelets  of  our 
other  genera  in  this  highly  specialized  group  present 


60  FIRST  BOOK  OF  GRASSES 

no  special  difficulty,  except  those  of  buffalo-grass, 
to  be  studied  later. 

SUMMARY 

In  this  group  the  spikelets  are  sessile  in  1 -sided 
spikes,  solitary,  digitate,  or  racemose.  In  most  of 
the  genera  the  upper  florets  are  sterile,  their  lemmas 
greatly  modified,  or  they  are  wholly  suppressed. 

REVIEW 

Collect  the  inflorescence  of  Bermuda-grass,  yard-grass,  any 
of  the  grama-grasses,  or  of  any  available  grass  with  1-sided 
spikes.  Note  the  arrangement  of  the  spikes  on  the  main  axis; 
distinguish  the  individual  spikelets  and  identify  their  parts. 


LESSON   IX 


DIVERSELY  SPECIALIZED  SPIKELETS 

IN  Lesson  IV, 
Fig.  22  (page  31), 
we  had  an  example 
of  fertile  and  ster- 
ile spikelets  in  the 
same  fascicle,  the 
fascicle  falling  as  a 
whole.  Because  the 
type  of  spikelet 
showed  kinship 
with  grasses  having 
many-flowered  lat- 
erally compressed 
spikelets,  Achy- 
rodes  is  placed  with 
them,  although  in 
its  fascicles  falling 
as  a  whole  it  forms 
an  exception.  In 
the  grasses  we  are 
about  to  study  in 
the  present  lesson, 
clustered  spikelets 
are  the  characteris- 
tic specialization. 


FlQ 


52  A)fascicle  of  &g0pogon  tenellus; 
B»  lemma,  and  C,  palea,  spread  out,  of 
sterile  spikelet;  D,  lemma  and  E,  palea  of 
perfect  spikelet. 

61 


62 


FIRST  BOOK  OF  GRASSES 


Examine  Fig.  52  (^Egopogon)  in  which  A  represents  a 
fascicle  (spread  apart)  of  one  fertile  and  two  sterile 
spikelets  attached  to  the  branch  which  falls  with 
them.  These  little  fascicles  are  racemose  and  nodding 
on  the  main  axis. 

In  Hilaria  (Fig.  53)  the  plan  is  the  same,  but  the 
fascicles  are  sessile  on  the  axis  and  erect,  the  spikelets 
are  sessile  in  the  fascicle,  the  glumes  are  elaborated 


FIG.  53.    A,  fascicle  of  Hilaria  Belangeri;  B,  glumes  (inner  face)  of  stami- 
nate  spikelet;  C,  two  views  of  perfect  spikelet;  D,  fertile  floret. 

and  very  unsymmetrical,  and  the  sterile  spikelets 
have  two  florets.  The  species  figured  is  the  com- 
monest one.  The  fascicles  of  some  of  the  other 
species  are  even  more  fantastic  than  these.  The 
glumes  and  lemma  are  always  sharply  folded  and 
compressed  laterally.  In  one  species  the  glumes  of 
the  sterile  spikelets  are  broad  and  fan-shaped,  in 
another  they  are  curiously  lobed  and  awned.  In 
all  the  species  they  are  exceedingly  variable,  but  in 
each  they  follow  a  general  pattern.  The  glumes  of 


DIVERSELY  SPECIALIZED  SPIKELETS 


63 


the  fertile  floret  are  often  slightly  adnate  to  (grown 
to)  those  of  the  sterile  spikelets,  making  the  fascicle 
somewhat  difficult  to  dissect.  It  is  in  such  cases  as 
this  that  the  fundamental  concept  of  the  structure 
of  a  grass  spikelet  enables  one  to  recognize  the 
spikelet  and  its  parts.  So  much  elaboration  for  the 
production  of  a  single  grain  is  very  exceptional  in 
grasses,  which  as  a  whole  tend  to  the  elimination  of 
non-essentials. 

A  third  grass  having  spikelets  in  little  fascicles  is 
Nazia  (see  Fig.  54).  This  is  probably  not  closely 
related  to  ^Egopogon 
and  Hilaria,  but  is 
commonly  grouped 
with  them  because 
of  its  fascicles  falling 
entire.  This  little 
bur-like  fascicle  is 
composed  of  two 
spikelets,  both  usu- 
ally perfect  (some- 
times with  a  third  reduced  one).  The  minute  first 
glumes  are  back  to  back,  and  the  large  second  glumes, 
covered  with  stout  hook-like  hairs,  face  outward. 
Note  that  the  glumes  are  not  folded  as  in  ^Egopogon 
and  Hilaria  but  convex.  These  spikelets  afford  an 
excellent  example  of  spine-like  hairs.  Hairs  are  an 
outgrowth  of  the  epidermis  (skin)  and  have  no 
connection  with  the  fibrous  structure  of  the  plant. 
The  " thorns"  of  the  rose  furnish  a  well-known 


FIG.  54.  A,  bur-like  fascicle  of  Nazia 
aliena;  B,  single  spikelet;  C,  floret. 


64 


FIRST  BOOK  OF  GRASSES 


example.  However  stout  they  may  be,  they  may 
readily  be  broken  from  the  bark  without  tearing 
the  wood.  The  thorns  of  hawthorns,  plums,  and 
locusts,  on  the  contrary,  however  slender,  can  not  be 
broken  off.  Being  reduced  branches,  the  woody 
fiber  (vascular  bundles)  extends  into  them  from  the 
skeleton  of  the  plant. 

In  all  the  spikelets  figured  heretofore  the  sterile 
florets  when  present  were  above  the  perfect  floret. 

In  a  group  of  grasses  repre- 
sented by  only  three  genera 
in  the  United  States,  the 
spikelets  bear  a  pair  of  sterile 
florets  below  the  single  per- 
fect floret  and  these  fall  at- 
tached to  the  fertile  one.  In 
sweet  vernal-grass,  or  An- 
thoxanthum  (Fig.  55)  the 
sterile  florets  consist  of 
empty  lemmas  unequally 
awned  from  the  back  and 
divided  above  the  insertion 
of  the  awn.  The  fertile  floret 
much  smaller,  awnless, 
A  be- 
ginner, in  dissecting  this 
spikelet,  might  mistake  this  fertile  floret  for  the 
grain  and  so  take  the  sterile  florets  for  a  lemma  and  a 
very  peculiar  palea.  Whenever  a  spikelet  or  any 
of  its  parts  seems  to  present  a  marked  departure 


is 


FIG.  55.   A,  spikelet  of  Anthox- 
anthum  odoratum;  B,  pair  of 
sterile  florets  below  the  per-     smooth,  and  shining, 
feet  floret;  C,  perfect  floret. 


DIVERSELY  SPECIALIZED  SPIKELETS          65 

from  the  normal  type  (such  as  a  1-awned  palea  would 
be),  it  is  advisable  to  reexamine  and  to  reconsider. 
A  close  examination  of  this  fertile  floret  will  reveal 
the  thin  edges  of  the  lemma  infolding  the  palea. 
A  grain  may  always  be  recognized  by  the  embryo 
at  the  base  on  the  back.  (See  Fig.  5,  A). 

In  Torresia  (called  holy-grass,  vanilla-grass,  or 
Seneca-grass)  the  sterile  florets  are  awnless  and  con- 
tain paleas  and  stamens.  Like  Anthoxanthum,  the 
whole  plant  is  fragrant.  These  are 
the  grasses  of  which  sweet-grass  bas- 
kets are  made. 

In  Phalaris  the  glumes  are  enlarged 
and  strongly  keeled  or,  as  in  canary- 
grass,  P.  canariensis  (Fig.  56),  wing- 
keeled,  and  the  sterile  florets  are  re- 
duced to  small  empty  lemmas.  In 
one  species,  P.  minor,  the  first  sterile 
floret  is  reduced  to  a  minute  rudi- 
ment, and  in  the  common  reed 
canary-grass,  P.  arundinacea,  both 
sterile  lemmas  are  narrow  and  hairy.  FlG  56  A"  spikelet 

In  Lesson  VII,  Fig.  42  (page  50),  we    of  Phalaris  cana- 

.       ,  ,  ,11-1      riensis;    B,    fertile 

had  an  example  of  greatly  reduced  floret  with  pair  of 
glumes.  In  rice,  Oryza  sativa  (Fig. 
57),  the  glumes  are  minute,  and  the 
lemma  and  palea  are  indurate  (hardened)  and  com- 
pressed laterally.  Some  varieties  of  rice  have  an 
awned  lemma.  In  an  allied  genus,  Homalocenchrus 
(Fig.  58),  the  glumes  are  wholly  suppressed. 


66 


FIRST  BOOK  OF  GRASSES 


FIG.  57.  Spike- 
let  of  rice 
(Oryza  saliva) . 


FIG.  58.  Spike- 
let  of  Homa- 
locenchrus  ory- 
zoides. 


In  Lesson  IV,  Figs.  23  (page  32)  and 
24  (page  32),  we  had  unisexual  spike- 
lets,  the  staminate  and  pistillate  on 
distinct  plants.  Wild  rice,  Zizania 
palustris  (Fig.  59,  A  and  B),  is  monoe- 
cious, staminate  and  pistillate  spikelets 
borne  in  the  same  panicle,  the  awn- 
less  staminate  ones  pendulous  on  the 
spreading  lower  branches,  the  awned 
pistillate  ones  erect  on  the  ascending 
upper  branches.  In  the  pistillate  spike- 
let  the  suppressed  glumes  are  repre- 
sented by  a  very  shallow  ridge  around 
the  base  of  the  spikelet.  The  staminate 
flower  consists  of  six  stamens  instead 
of  three,  as  in  the  grasses  studied  here- 
tofore. The  palea  of  this  spikelet  is 


FIG.  59.  A,  pistillate  spikelet,  and  B,  staminate  spike- 
let,  of  Zizania  palustris. 


DIVERSELY  SPECIALIZED  SPIKELETS         67 

anomalous  in  that  it  has  three  nerves.  Throughout 
the  grasses  the  palea  has  two  nerves,  rarely  sup- 
pressed, as  in  Agrostis,  where  the  palea  itself  is  much 
reduced,  or  so  close  together  as  to  be  merged  into  one, 
but  in  no  case  are  more  than  two  nerves  known.  The 
problem  presented  by  this  spikelet  has  not  been  sat- 
isfactorily solved.  It  is  possible  that  the  two  organs 
are,  respectively,  the  second  glume  and  the  lemma, 
the  first  glume  and  the  palea  being  suppressed.  In 
the  pistillate  spikelet  the  palea  is  2-nerved.  In  the 
perennial  wild  rice  of  the  southeastern  states,  Zizani- 
opsis  miliacea,  this  3-nerved  organ  is  present  in  both 
the  staminate  and  pistillate  spikelets,  and  in  another 
related  genus,  Luziola,  both  bracts  of  the  spikelets 
are  several  to  many  nerved. 

SUMMARY 

In  the  highly  specialized  spikelets  studied  in  this 
lesson  the  various  organs  are  identified  (1)  by  their 
position,  bearing  in  mind  that  the  bracts  of  a  spikelet 
are  2-ranked  and  alternate  on  the  rachilla,  and 
(2)  by  their  resemblance  to  corresponding  organs  in 
allied  grasses. 

REVIEW 

Hilaria,  Nazia,  and  ^Egopogon  are  found  only  in  the  South- 
west, but  the  other  grasses  studied  in  this  lesson  are  widespread. 
In  any  region  in  the  United  States  will  be  found  one  or  more  of 
them.  Collect  any  that  are  available,  examine  the  inflorescence, 
distinguish  the  spikelets,  and  identify  their  parts. 

If  in  a  species  of  Phalaris  but  one  sterile  floret  is  found  below 
the  perfect  one,  how  can  you  tell  which  of  the  pair  is  suppressed? 


LESSON  X 

SPIKELETS  WITH  MEMBRANACEOUS  GLUMES 
AND  HARDENED  FRUITS 

ALL  the  spikelets  heretofore  studied  have  been 
more  or  less  compressed  laterally  (that  is,  a  detached 
spikelet  under  observation  lies  on  its  side,  the  two 
ranks  of  glumes  and  lemmas  to  right  and  left  of  the 
rachilla,  as  in  Figs.  11-14)  and,  with  relatively  few 
exceptions,  the  articulation  has  been  above  the 
glumes,  these  remaining  on  the  pedicel  after  the  fall 
of  the  florets.  These  two  characters  in  common 
pertain  to  more  than  half  of  all  our  grasses.  In 
many  of  the  laterally  compressed  spikelets  the 
florets  themselves  are  dorsally  compressed  (see 
Fig.  11,  B).  We  come  now  to  a  lesser  group,  in 
which  the  spikelets  are  dorsally  compressed  (the 
spikelet  under  observation  lying  on  its  face  or  back, 
the  two  ranks  above  and  below  the  rachilla).  In 
this  group  of  grasses  the  rachilla  joints  are  usually 
so  short  that  the  glumes  and  lemmas  are  borne  one 
immediately  above  the  other.  The  rachilla  is  never 
prolonged  beyond  the  base  of  the  fertile  floret,  as  in 
many  of  the  spikelets  heretofore  studied. 

Examine  Fig.  60.  Note  that  the  first  glume  is 
much  smaller  than  the  second.  Turn  to  Fig.  11 
(page  25).  In  imagination,  remove  the  glumes  and 

68 


SPIKELETS  WITH  HARDENED  FRUITS 


69 


all  but  the  two  lower  florets.  The  result  is  compara- 
ble to  the  two  florets  (Fig.  60,  C)  of  Panicum,  but 
in  this  genus  the  lower  floret  is  staminate  or  sterile, 
and  its  lemma  and  palea  differ  in  form  and  texture 
from  those  of  the  perfect  floret  (Fig.  60,  D).  The 
sterile  lemma  (commonly  termed  the  " third  glume" 
in  all  but  recent  books)  resembles  the  second 
glume  and  incloses  a  small  thin  palea,  while  the 


FIG.  60.  A,  spikelet  of  Panicum  miliaceum,  side  view;  B,  same 
seen  from  the  back;  C,  sterile  and  fertile  florets  removed 
from  the  glumes,  side  view;  D,  fertile  floret. 

fertile  lemma  is  indurate,  its  nerves  obscured  in  the 
thickened  tissue,  and  firmly  clasps  a  palea  of  like 
texture.  At  maturity  the  gram  is  inclosed  in  this 
fast-locked  little  case  (the  whole  commonly  termed 
the  fruit)  and  germinates  within  it,  sending  its  rootlet 
through  a  thin  place  near  the  base  of  the  lemma 
(seen  as  a  crescent-shaped  depression  at  the  back) 
and  thrusting  its  sprout  between  the  lemma  and 
palea  at  the  summit  or  side.  In  dissecting  a  spikelet 
of  Panicum  or  its  related  genera  the  palea  of  the 


70 


FIRST  BOOK  OF  GRASSES 


sterile  floret  often  adheres  to  the  palea  side  of  the 
fruit  (the  mature  fertile  floret)  as  a  small  thin  scale, 
difficult  for  the  beginner  to  account  for  unless  he 
understands  the  structure  of  the  spikelet. 

This  type  of 
spikelet  is  charac- 
teristic of  the  large 
number  of  grasses 
forming  the  millet 
tribe.  In  Panicum 
the  inflorescence  is 
an  open  or  con- 
tracted panicle.  In 
crab-grass,  Synthe- 
risma  sanguinalis 
(Fig.  61)  and  its 
relatives,  the  spike- 
lets  are  borne  in 
1 -sided  racemes, 
much  like  those 
of  Bermuda-grass 
(Fig.  48).  In  the 
crab-grasses  the 
first  glume  is  mi- 
nute or  suppressed,  and  the  second  is  commonly 
much  shorter  than  the  sterile  lemma  and  the  fertile 
floret.  The  fertile  lemma  and  its  palea  are  less 
indurate  than  those  of  Panicum  and  the  margin  of 
the  lemma  is  thin  in  texture  and  flat  instead  of  being 
firm  and  inrolled,  as  in  Panicum. 


FIG.  61.  A,  two  views  of  spikelet  of  Synthe- 
risma  sanguinalis;  B,  fertile  floret;  C,  in- 
florescence. 


SPIKELETS  WITH  HARDENED  FRUITS 


71 


In  Paspalum  (Fig.  62)  the  spikelets  are  more  like 
those  of  Panicum  in  texture,  and  the  margin  of  the 
fertile  lemma  is  firm  and  inrolled,  as  in  that  genus. 
The  first  glume  is  wholly  suppressed  except  in  a  few 
species.  The  spikelets  are  subsessile  in  two  rows  on 
one  side  of  a  rachis,  either  single  (Figs.  62  and  63,  A) 


FIG.  62. 


A,  two  views  of  spikelet  of  Paspalum 
;  B,  fertile  floret;  C,  inflorescence. 


FIG.  63.  A,  rachis  of 
Paspalum  Iceve,  spike- 
lets  removed;  B,  ra- 
chis of  a  Paspalum 
with  paired  spikelets; 
C,  cross-section  of 
rachis,  showing  raised 
center  and  thin  mar- 
gins. 


or  in  pairs  (Fig.  63,  B).  [In  descriptions  these  are 
often  referred  to  as  2-rowed  or  4-rowed,  respectively.] 
In  species  with  paired  spikelets  some  of  the  secondary 
ones  (those  next  the  center  of  the  rachis)  are  always 
abortive.  The  racemes  in  Paspalum  are  sometimes 
solitary  and  sometimes  digitate,  as  in  Syntherisma, 


72 


FIRST  BOOK  OF  GRASSES 


but  more  commonly  they  are  racemose  on  the  main 
axis  (as  in  Fig.  62).  The  rachis  is  sometimes  winged, 
and  in  a  few  species  the  broad  wings  fold  up  over  the 
base  of  the  spikelets. 

In  Reimarochloa  (represented  by  but  one  species 
in  the  United  States)  the  spikelets  are  arranged  as 
in  Paspalum,  but  both  glumes  are  suppressed  except 

in  the  uppermost 
spikelet.  (Recall 
Lolium,  Lesson  V, 
Fig.  27,  page  36). 
If  it  were  not  for  its 
obvious  relation- 
ship to  Paspalum, 
in  which  an  occa- 
sional first  glume  is 
developed  in  sev- 
eral species  and  reg- 
ularly in  a  few,  the 
spikelet  of  Reima- 
rochloa might  be 
taken  to  be  strictly 
1-flowered  with 
only  the  first  glume 
suppressed  except  in  the  terminal  spikelet. 

In  Paspalum  we  have  seen  a  slightly  broadened 
rachis  (Fig.  63).  In  Stenotaphrum,  or  St.  Augustine- 
grass  (Fig.  64),  the  rachis  is  broad,  thick,  and  corky, 
and  the  spikelets  are  partly  embedded  in  it.  At 
maturity  the  rachis  breaks  up  into  short  joints  with 


FIG.  64.  A,  part  of  raceme  of  Stenotaphrum 
secundatum,  front  view  showing  spikelets; 
B,  back  view  of  three  joints. 


SPIKE  LETS  WITH  HARDENED  FRUITS 


73 


the  spikelets  attached.    (Recall  Lepturus,  Lesson  V, 
Fig.  28,  page  37.) 

In  Syntherisma,  Paspalum,  Reimarochloa,  and 
Stenotaphrum,  with  subsessile  spikelets  borne  on  one 
side  of  a  rachis,  the  spikelets 
are  placed  with  the  back  of  the 
fertile  lemma  against  the  rachis, 
that  is,  with  the  first  glume 
(developed  or  hypothetical), 
sterile  lemma,  and  the  palea  of 
the  fertile  floret  outward.  In 
Axonopus  (Fig.  65),  Brachiaria, 
and  Eriochloa  the  spikelets  are 
reversed,  the  back  of  the  fertile 
lemma  being  turned  from  the 
rachis  and  the  palea  toward 
it.  In  Axonopus  the  first  glume 
is  wholly  suppressed.  In  Erio- 
chloa (Fig.  66)  the  first  glume 

is    reduced 

to      a     m  i- 

nute    sheath 

around     the 

enlarged  rachilla  joint  below  the 

second  glume  and  grown  fast  to  it. 

The  fertile  lemma  is  tipped  with 

a  minute  awn,  which  breaks  off 

readily. 
FIG.  66.  A,  spikeiet  of       In  barnyard-grass,   Echinochloa 

Crusgalli,  is  the  same  type  of  spike- 


FIG.  65.  A,  part  of  raceme 
of  Axonopus  furcatus;  B, 
inflorescence;  C,  cross- 
section  of  rachis. 


74 


FIRST  BOOK  OF  GRASSES 


let  as  in  Panicum,  but  the  second  glume  and  sterile 
lemma  are  awned  or  awn-tipped,  and  the  pointed 
tip  of  the  palea  is  not  inclosed  in  the  lemma,  which 
also  is  sharp-pointed.  The  glumes  and  sterile  lemma 
bear  spine-like  hairs,  but  not  so  thick  as  those  of 
Nazia. 

Observe  the  diagrammatic  panicle  in  Fig.  67,  A. 
In  imagination,  remove  all  the  terminal  spikelets 


FIG.  67.  A,  diagrammatic 
panicle;  B,  two  branches 
of  panicle  with  terminal 
spikelets  removed. 


^r  FIG.  68.  Small  part  of  bristly 
panicle  of  Chcetochloa  Grise- 
bachii. 


from  a  branch.  The  result  is  Fig.  67,  B.  Compare 
Fig.  68  with  this.  It  will  be  seen  that  the  bristles 
of  the  latter  are  branches  of  the  panicle  which  are 
without  spikelets  at  their  tips  but  which  bear  sub- 
sessile  spikelets  at  or  toward  their  base.  This 


SPIKELETS  WITH  HARDENED  FRUITS         75 


modification  of  sterile  branches  and  branchlets  into 
rough  bristles  is  found  in  the  millets  (Chsetochloa), 
common  millet,  yellow  foxtail,  and  green  foxtail. 
These  branchlets  are  the  "  involucre  of  bristles " 
referred  to  in  many  manuals  and  descriptions.  The 
spikelets  fall  from  their 
pedicels,  as  in  Panicum, 
and  the  bristles  remain 
on  the  axis.  In  most 
of  the  species  the  pani- 
cles are  dense  and 
spike-like,  the  spikelet- 
bearing  branches  fas- 
cicled '  and  very  short 
and  the  sterile  ones,  or 
bristles,  long  and  slen- 
der. In  yellow  fox- 
tail, Chcetochloa  lute- 
scens  (Fig.  69),  the  fas- 
cicle consists  of  several 
branches,  only  one  of 
them  spikelet-bearing,  FIG<  69.  A 
the  others  transformed 
into  slender  bristles. 
Between  the  ordinary  panicle  represented  in  Fig.  67 
and  the  bristly  spike-like  one  of  yellow  foxtail  (Fig. 
69,  B)  there  is  every  degree  of  gradation. 

A  further  specialization  of  sterile  branches  is  shown 
in  the  sand-burs  (Cenchrus).  Compare  Fig.  70  with 
Fig.  69,  A. .  Instead  of  the  nearly  simple  fascicle  of 


fascicle  from  panicle  of 
Chcetochloa  lutescens;  B,  spike-like 
panicle  of  same. 


76 


FIRST  BOOK  OF  GRASSES 


branchlets  found  in  the  millets,  the  sand-burs  have  a 
complex  fascicle  of  many  compound  branches.  The 
primary  branches  disarticulate  from  the  axis,  and 
the  whole  fascicle,  or  bur,  falls  entire  with  the  spike- 
let  permanently  inclosed,  the  grain  eventually 
germinating  within  it.  The  simplest  form  of  sand- 
bur  is  in  Cenchrus  myosuroides  (Fig.  70).  The  struc- 
ture of  this  will  be  comprehended  if  we  conceive  of 


FIG.  70.    Bur  of  Cenchrus 
myosuroides. 


FIG.  71.  Bur  of  Cenchrus  pauciflorus. 


a  dense  fascicle  of  branches  with  but  one  of  them 
bearing  a  single  sessile  spikelet,  the  others  branching 
at  the  base  and  surrounding  the  spikelet-bearing  one. 
In  the  common  inland  sand-bur,  Cenchrus  pauci- 
florus (Fig.  71),  the  sterile  branches  are  much  thick- 
ened and  flattened  and  are  grown  together  below, 
their  free  summits  sharp  and  spine-like.  The  nu- 
merous secondary  branchlets,  in  the  form  of  stout 
spines,  spread  from  the  body  of  the  bur  formed  by 
the  cohesion  of  the  main  branches  surrounding  the 
one  or  few  sessile  spikelets. 


SPIKELETS  WITH  HARDENED  FRUITS 


77 


In  all  the  seed-bearing  spikelets  so  far  examined, 
the  stamens  and  stigmas  project  at  flowering  tune, 
resulting  in  cross  fertilization  of  the  ovules.  A  few 
grasses  bear  cleistogamous  (close-fertilized)  as  well  as 
openly  fertilized  spikelets. 
Such  spikelets  do  not 
open,  and  there  is  usually 
but  a  single  small  stamen 
which  empties  its  pollen 
directly  on  the  short  stig- 
mas. The  grain  is  larger 
than  that  of  open-fer- 
tilized spikelets.  Two  of 
our  native  grasses,  form- 
ing the  genus  Amphicar- 
pon,  related  to  Panicum,  FlG-  72- 
are  remarkable  in  that 
they  produce  large  cleistogamous  spikelets  under- 
ground from  subterranean  branches  (Fig.  72).  The 
plants  also  bear  terminal  panicles  of  ordinary  and 
much  smaller  spikelets,  but  these  seldom  perfect 
seed. 

SUMMARY 

In  Panicese,  the  millet  tribe,  the  spikelets  fall 
entire.  They  bear  one  perfect  floret  with  a  sterile 
floret  below  it.  The  lemma  and  palea  of  the  perfect 
floret  are  indurate.  The  sterile  lemma  resembles  the 
second  glume,  the  two  simulating  a  pair  of  glumes, 
while  the  first  glume  is  small  and  looks  like  an  addi- 


78  FIRST  BOOK  OF  GRASSES 

tional  one  (in  some  older  works  it  is  called  the  acces- 
sory valve  or  glume)  or  is  entirely  suppressed.  The 
genera  differ  chiefly  in  the  arrangement  of  the  spike- 
lets  hi  the  inflorescence.  In  a  few  genera  some  of  the 
panicle  branches  are  without  spikelets  and  are 
transformed  into  bristles  or  burs. 

REVIEW 

Collect  the  inflorescence  of  broom-corn  millet,  old  witch-grass, 
or  of  as  many  species  of  Panicum  as  are  available,  and  dissect 
the  spikelets.  Collect  heads  of  barnyard-grass  and  compare  the 
spikelets  with  those  of  Panicum.  Compare  the  spine-like  hairs 
with  those  of  Nazia,  Fig.  54. 

Collect  the  inflorescence  of  crab-grass  and  of  any  species  of 
Paspalum  available;  note  the  arrangement  of  spikelets  and  com- 
pare the  form  and  texture  of  the  fruit  (fertile  floret)  with  that  of 
Panicum. 

Collect  heads  of  common  millet  or  of  yellow  or  green  foxtail. 
Remove  enough  branches  from  the  axis  to  show  clearly  the  form 
and  arrangement  of  the  few  remaining. 

If  available,  examine  a  sand-bur,  splitting  the  bur  with  a 
sharp  knife. 


LESSON  XI 

PAIRED  SPIKELETS  WITH  HARDENED  GLUMES 
AND  THIN  LEMMAS 

IN  the  sorghum  tribe,  which  we  are  about  to  study, 
the  spikelet,  as  in  the  millet  tribe,  falls  entire  and  is 
dor  sally  compressed,  but  the  glumes  are  hardened 
and  the  lemmas  thin,  while  in  the  millet  tribe  the 
glumes  are  thin  and  the  fertile  lemma  and  palea  are 
hardened.  The  glumes  entirely  inclose  the  two 
florets.  The  midnerve  of  the  first  glume  is  com- 
monly suppressed,  while  a  pair  of  nerves  near  the 
margin  is  often  prominent  and  sometimes  keeled,  or 
even  winged.  The  second  glume  may  be  like  the 
first  or  the  midnerve  may  be  slightly  keeled.  The 
lower  floret  consists  of  an  empty  lemma  only,  the 
upper  of  a  perfect  flower  with  a  small  thin  often 
awned  lemma  (sometimes  so  small  as  to  appear 
like  a  bit  of  membrane  at  the  base  of  the  awn)  and  a 
minute  palea  (sometimes  suppressed). 

Examine  Fig.  73,  A,  and  compare  it  with  Figs.  21 
(p.  30),  22  (p.  31),  30  (p.  40),  40  (p.  49),  52  (p.  61), 
and  53  (p.  62).  In  all  the  figures  referred  to,  fertile 
spikelets  are  associated  with  sterile  ones.  These 
are  grouped  in  various  ways.  In  the  sorghum  tribe 
the  typical  arrangement  is  a  jointed  raceme  with  a 
sessile  perfect  spikelet  and  a  pediceled  sterile  spikelet 

79 


80 


FIRST  BOOK  OF  GRASSES 


(staminate  or  neuter)  at  each  joint,  the  rachis  dis- 
articulating at  the  summit  of  each  joint,  this  and  the 
pedicel  of  the  sterile  spikelet  remaining  attached  at 

their  base  to  the  per- 
fect spikelet  as  a  pair 
of  little  stalks.  In 
this  group  of  grasses 
specialization  consists 
chiefly  in  modifications 
of  the  axes  of  inflores- 
cence and  secondarily 
in  the  modification  of 
the  spikelets.  In  Fig. 
73,  A  (Johnson-grass, 
Holcus  halepensis) ,  are 
two  views  of  a  single 
joint,  consisting  of  the 
sessile  perfect  spikelet 
with  the  attached  ra- 
chis joint  and  the  ped- 
icel with  its  staminate 
spikelet.  Fig.  73,  B,  is 
a  diagram  of  a  raceme 

FIG.  73,    A,  two  views  of  single  joint  of  four  SUCh  joints  and 

of  raceme  of   Holcus  halepensis;  B,  73    Q    a  diagram  of  the 
diagram   of   raceme   of  four   joints;  ,  .  ..         ,.      .        , 

C,  diagram  of  rachis  and  pedicels;  D,  raCfllS  and  pedicels,  trie 

inflorescence.  spikelets  removed  and 

the  points  of  disarticulation  shown  by  dotted  lines. 
In  sorghum,  or  Holcus,  these  little  racemes  are  borne 
on  the  ultimate  branchlets  of  a  panicle  (Fig.  73,  D). 


PAIRED  SPIKELETS 


81 


In  the  closely  related  Indian-grass,  Sorghastrum,  the 
racemes  are  reduced  to  one  or  two  joints,  and  the 
sterile  spikelets  are  wholly  suppressed,  the  slender 
hairy  pedicel  alone  being  developed. 

Compare  F  i  g. 
74,  A,  a  diagram- 
matic single  joint 
of  Erianihus  sac- 
charoides,  with  Fig. 
73,  A,  and  Fig.  74, 
B,  three  joints  of  a 
long  raceme,  with 
Fig.  73,  B.  It  will 
be  seen  that,  while 
the  spikelets  are 
paired,  the  pedi- 
celed  spikelet  is  as 
large  as  the  sessile 
one  and,  like  it, 
is  awned.  In  this 
genus  the  pediceled 
spikelet  is  usually 
perfect.  The  ra- 
cemes are  long  and  , 

,  ,  FIG.  74,  A,  diagram  of  single  joint  of  raceme 

Slender       and       CO-        of  Erianthus  saccharoides;  B,  three  joints 

piously  hairy,  and     ofraceme- 

are  crowded  on  a  stout  main  axis  forming  large, 
dense,  woolly  panicles.  In  sugar-cane  the  inflores- 
cence is  like  that  of  Erianthus,  but  the  spikelets 
are  awnless. 


82 


FIRST  BOOK  OF  GRASSES 


Examine  Fig.  75,  A,  a  joint  of  a  raceme  of  one  of 
the  broom  sedges  (Andropogon  scoparius).  It  will 
be  seen  to  have  the  same  general  plan  as  a  joint  of 
sorghum,  and  the  racemes,  shown  in  Fig.  75,  B, 

though  slender  and  flex- 
uous,  are  in  structure 
similar  to  the  racemes  of 
sorghum.  The  entire  in- 
florescence, however,  is 
very  different.  In  sorg- 
hum and  Erianthus  the 
inflorescence  is  a  leafless 
terminal  panicle,  such  as 
is  common  in  grasses. 
The  diagrammatic  inflores- 
cence (Fig.  75,  B)  shows 
that  the  racemes  of  the 
broom-sedge  are  borne  on 
numerous  slender  leafy 

of  Andropoion "  scoparius;  B,   branches    arising    in    the 
r2cencpeart  * compound  ™°~  axils    of    leaves    on    the 

main    culm   or   branches, 

the  whole  forming  a  compound  inflorescence.  The 
leaves,  especially  the  ultimate  ones  immediately 
below  the  racemes,  are  mostly  reduced  to  blade- 
less  sheaths  and  are  sometimes  bright  colored. 
Such  transformed  leaves  subtending  or  surround- 
ing single  inflorescences  are  commonly  termed 
spathes. 

In  some  species  the  racemes  are  partly  inclosed 


FIG.  75.  A,  single  joint  of  raceme 


PAIRED  SPIKELETS 


83 


in  the  spathes.  The  racemes  may  be  solitary  (that 
is,  one  to  a  branch,  as  shown)  or  two  to  several, 
digitate,  on  a  single  branch.  In  some  species  the 
sterile  spikelet  is  suppressed,  only  the  pedicel  being 
developed.  In  a  few  species  of  Andropogon  the 
racemes  are  in  leafless  panicles, 
as  in  Erianthus,  but  the  pedi- 
celed  spikelets  are  sterile  and 
awnless. 

Examine  Fig.  76,  A  (Mani- 
suris  cylindrica),  and  compare 
it  with  73,  A.  In  Holcus  and 
Erianthus  the  rachis  joint  and 
the  pedicel  of  the  second  spike- 
let  are  about  equal  in  thick- 
ness. In  Fig.  75  the  rachis 
joint  is  stouter  than  the  pedi- 
cel. In  Manisuris  the  rachis 
joint  is  greatly  thickened  and 
hollowed  out  below  on  the  inner 
face.  (See  Fig.  28,  p.  37,  for  an  F  7, 

v  ?        /          ,  .  FlG-  76>  A »  single    joint  of 

earlier  example  of  a  thickened  raceme  of  Manisuris 
rachis.)  The  pedicel  of  the  ster- 
ile spikelet  is  also  thickened, 
but  much  less  so,  and  the  two 
lie  close  together  (instead  of 
spread  apart,  as  in  Figs.  73  to  75)  and  entirely  cover 
the  second-glume  side  of  the  spikelet  which  fits  into 
the  cavity  formed  by  the  rachis  joint  and  pedicel. 
Fig.  76,  C,  shows  the  inner  faces  of  the  rachis"  joint 


lindrica;  B,  another  view 
of  two  joints;  C,  inner  face 
of  rachis  joint  and  pedi- 
cel, spikelet  removed;  D, 
part  of  cylindrical  many- 
jointed  raceme. 


84 


FIRST  BOOK  OF  GRASSES 


and  pedicel,  the  perfect  spikelet  removed.  The 
spikelets  are  awnless  and  the  marginal  nerves  of  the 
first  glume  are  winged  at  the 
summit.  This  inflorescence  and 
that  of  Lepturus  (Fig.  28)  are  so 
similar  in  appearance  and  func- 
tion, disjointing  with  the  mature 
seed  permanently  attached,  that 
the  student  may  wonder  why 
they  are  placed  in  tribes  so  re- 
mote as  the  barley  grasses  and 
sorghum.  The  two  illustrate 
what  is  not  seldom  shown  in 
nature,  that  very  different  struc- 
tures may  arrive  at  the  same 
function,  although  the  forms 
from  which  they  are  derived  were 
very  remote.  The  inflorescence 
of  Lepturus  is  a  spike,  and  its 
FIG.  77?  A,  single  joint  of  spikelet  shows  it  to  be  a  reduced 
raceme  of  Rytnix  granu-  and  specialized  relative  of  Lo- 

laris;  B,   reverse  view;    v  rrn       .    a  „  ,  T 

c,  diagram  of  rachis  num.    Ine  inflorescence  01  Mani- 

and   pedicels    of    three    gur  jg  jg  a  raceme  with  tWO  Spike- 
jomts  of  raceme,  spike-  .  •      »'-  i 

lets  removed;  D,  view  lets  at  a  joint,  one  pediceled,  and 
giUToTse^LpLett;  the  perfect  spikelet  not  greatly 
E,  raceme;  F,  reverse  different  from  that  of  sorghum. 
We   have   just  observed  the 
rachis  joint  and  pedicel  lying  closely  pressed  together. 
In  Rytilix  (Fig.  77,  A)  they  are  adnate  (grown  to- 
gether).   Examine  the  diagram  of  three  joints  with 


PAIRED  SPIKELETS  85 

the  spikelets  removed  (Fig.  77,  C)  and  note  that  the 
rachis  joints  (the  thicker  parts)  form  a  central  axis 
with  the  pedicels  borne  on  alternate  sides,  just  as  they 
are  in  Holcus  (Fig.  73,  C).  In  this  raceme  we  have 
just  the  reverse  of  the  arrangement  of  Manisuris.  In 
that,  the  fertile  spikelet  fits  into  a  cavity  formed 
by  the  rachis  joint  and  pedicel  while  in  Rytilix  the 
rachis  joint  and  pedicel  fit  into  a  cavity  formed  by 
the  fertile  spikelet.  (See  Fig.  77,  D,  showing  the 
inside  face  of  the  first  glume  of  the  perfect  spikelet, 
and  examine  the  two  views  of  the  joints,  A  and  B, 
and  the  two  views  of  the  raceme,  E  and  F).  The 
sterile  spikelet  is  well  developed  but  usually  contains 
no  flower.  The  perfect  spikelet  with  its  peculiar 
gray,  ridged  and  pitted,  subglobose  first  glume  sug- 
gests the  achene  of  some  species  of  Scleria  (a  sedge). 
The  whole  inflorescence  is  very  unlike  that  of  any 
other  known  grass. 

Return  to  Fig.  73,  A,  and  compare  with  it  Fig. 
78,  A  (Rhaphis  pauciflora),  which  shows  a  raceme 
reduced  to  a  single  joint  consisting  of  the  sessile 
perfect  spikelet  and  two  pediceled  sterile  spikelets, 
the  rachis  joint  (found  in  Holcus  and  the  others 
studied)  often  being  replaced  by  a  second  pedicel  and 
sterile  spikelet.  This  second  sterile  spikelet  is  not 
always  developed.  In  Rhaphis  this  1-jointed  raceme 
has  a  sharp  hairy  callus  at  the  base.  Fig.  78,  B  (the 
base  of  a  raceme  and  the  summit  of  a  branch,  the 
hairs  removed),  shows  the  source  of  this  callus.  The 
racemes  are  borne  on  the  long  slender  branches  of  a 


86 


PlRST  BOOK  OF  GRASSES 


spreading  panicle  (Fig.  78,  D)  which  disarticulate 
obliquely  below  the  raceme,  the  line  of  articulation 
bordered  by  a  dense  brush  of  hairs  (Fig.  78,  C).  The 


FIG.  78.  A,  one-jointed  raceme  of       FIG.  79.    A,  single  joint  of  raceme 


Rhaphis  pauciflora;  B,  base  of 
raceme  and  summit  of  branch; 
C,  hairy  summit  of  branch  from 
which  raceme  has  fallen;  D,  in- 
florescence. 


of  Heteropogon  contortus;  B,  per- 
fect spikelet  from  which  sterile 
spikelet  has  fallen ;  C,  base  of  fer- 
tile spikelet  and  its  callus;  D,  ra- 
ceme; E,  diagram  of  raceme; 
F,  diagram  of  rachis  and  pedicels 
of  four  joints  of  raceme. 


sterile  spikelets  with  their  pedicels  fall  off  before  the 
maturity  of  the  perfect  spikelet,  which,  with  its 
hairy  callus  and  long  awn,  closely  resembles  a  mature 
floret  of  Stipa  (Fig.  45). 


PAIRED  SPIKELETS  87 

In  Heteropogon  (Fig.  79)  is  a  more  complicated 
arrangement.  In  A  is  shown  a  joint  of  the  raceme, 
consisting  of  the  sessile  perfect  awned  spikelet  and 
the  pediceled  large  pale  sterile  spikelet,  with  the 
short  hairy  rachis  joint  below  forming  a  pointed 
callus.  In  Fig.  79,  C,  is  seen  the  base  of  the  fertile 
spikelet  and  the  callus,  with  enough  hairs  removed  to 
expose  the  very  base  of  the  pedicel,  which  has  fallen 
with  the  sterile  spikelet,  and  (to  the  left)  the  oblique 
scar  from  which  the  rachis  joint  next  above  has 
disarticulated.  The  articulation  is  at  the  base  of  the 
rachis  joint  instead  of  at  the  summit,  as  in  Holcus 
and  the  others  (Figs.  73-77),  and  forms  a  callus  to  the 
spikelet  next  above.  The  rachis  joints  are  very 
short  and  the  fertile  spikelets  (except  their  awns)  are 
hidden  by  the  overlapping  sterile  spikelets,  the  long 
flexuous  awns  forming  a  tangle  beyond  the  end  of  the 
raceme  (Fig.  79,  D).  Besides  having  this  modified 
rachis  and  large  unsymmetrical  sterile  spikelets,  the 
raceme  of  Heteropogon  presents  a  further  modifica- 
tion in  that  its  lower  two  or  three  pairs  of  spikelets 
are  all  sterile,  instead  of  each  pair  consisting  of  a 
perfect  and  a  sterile  one,  as  typical  for  the  sorghum 
tribe.  In  these  lower  pairs  the  sessile  spikelet  is 
staminate  and  the  pediceled  one  empty,  but  both 
have  large  unsymmetrical  glumes  and  appear  to  be 
alike.  Examine  the  diagram  of  the  raceme  (Fig. 
79,  E,  the  rachis  greatly  lengthened  to  show  the 
structure  and  arrows  indicating  the  points  of  dis- 
articulation)  and  contrast  it  with  Fig.  73,  B.  Fig. 


88  FIRST  BOOK  OF  GRASSES 

79,  F,  is  a  diagram  of  the  rachis  of  four  joints,  show- 
ing the  points  of  disarticulation.  Contrast  it  with 
Fig.  73,  C. 

The  mature  fertile  spikelets  of  Rhaphis  and 
Heteropogon  closely  resemble  mature  fruits  of  Stipa 
and  function  in  the  same  way,  disseminating  the  seed 
by  attaching  themselves  by  their  sharp  calluses  to 
passing  animals  and  securing  their  hold  by  the  un- 
twisting and  twisting  of  their  hygroscopic  (moisture- 
sensitive)  awns.  They  afford  another  example  of 
the  same  function  performed  by  different  organs. 

SUMMARY 

The  grasses  of  the  sorghum  tribe  have  spikelets 
with  hardened  glumes  and  thin  lemmas.  Typically 
they  are  arranged  in  pairs,  one  sessile  and  perfect, 
the  other  pediceled  and  sterile  on  a  jointed  rachis, 
forming  racemes.  In  several  genera  the  rachis  is 
elaborately  modified. 

REVIEW 

Collect  the  inflorescence  of  Johnson-grass  and  of  any  of  the 
broom-sedges.  Break  the  raceme  into  single  joints,  noting  the 
points  at  which  it  readily  separates.  Examine  the  spikelets  and 
the  rachis  and  distinguish  the  rachis  joint  from  the  pedicel. 

If  you  had  a  panicle  of  Rhaphis  (Fig.  78,  D)  from  which  all 
the  sterile  spikelets  with  their  pedicels  had  fallen,  how  would 
you  know  it  was  not  a  species  of  Stipa? 

Make  diagrams  of  the  inflorescence  of  any  available  species 
of  the  sorghum  tribe. 


LESSON   XII 


HIGHLY  SPECIALIZED  UNISEXUAL 
SPIKELETS 


EXAMINE  Fig.  80, 
gama-grass  (Tripsacum 
dactyloides) .  This  grass 
is  monoecious  (see  p.  23). 
The  pistillate  spikelets 
are  borne  on  the  lower 
part  of  the  one  to  three 
stout  digitate  racemes 
and  the  staminate  spike- 
lets  on  the  upper  part  of 
the  same  racemes  (Fig. 
80,  D).  The  part  of  the 
rachis  bearing  the  stami- 
nate spikelets  is  rela- 
tively slender  and  falls 
off  after  flowering  time; 
the  part  bearing  the  pis- 
tillate spikelets  is  greatly 
thickened  and  disarticu- 
lates with  the  spikelets 
permanently  embedded 
in  the  joints.  Fig.  80,  A, 
shows  two  joints  with 
spikelets  embedded ;  B,  a 


FIG.  80.  A,  two  joints  of  pistillate 
part  of  raceme  of  Tripsacum  dac- 
tyloides;  B,  spikelet  removed  from 
the  joint;  C,  rachis  joint  from 
which  spikelet  has  been  removed; 
D,  inflorescence;  E,  diagram  of 
rachis  of  pistillate  part;  F,  pair 
of  staminate  spikelets. 


90  FIRST  BOOK  OF  GRASSES 

spikelet  removed  from  its  joint;  C,  the  joint  from 
which  a  spikelet  has  been  removed;  and  E,  a  diagram 
of  the  rachis.  Compare  the  joints  with  those  of 
Manisuris  (Fig.  76).  Note  that  in  Tripsacum  the 
pistillate  part  is  a  simple  spike  with  no  vestige  of  a 
second  spikelet.  The  structure  of  the  spikelet  is 
similar  to  that  of  spikelets  of  the  sorghum  tribe,  hav- 
ing firm  glumes  (the  first  hard  and  like  the  rachis 
joint  in  texture),  a  thin  sterile  lemma,  and  a  very 
thin  fertile  lemma  and  palea.  The  staminate  spike- 
lets  are  in  pairs  (Fig.  80,  F)  and  one  of  each  pair  is 
usually  on  a  very  short  pedicel.  The  glumes  are 
much  like  those  of  different  species  of  Andropogon; 
both  florets  are  staminate,  their  lemmas  and  paleas 
thin. 

Indian  corn,  or  maize  (Zea  Mays),  the  most 
highly  specialized  grass  known,  is  believed  to  be 
related  to  Tripsacum.  It  is  monoecious,  but  the 
staminate  and  pistillate  spikelets  are  borne  in  distinct 
inflorescences.  The  staminate  spikelets  are  in  pairs 
on  a  slender  rachis  forming  racemes,  these  arranged 
in  a  panicle,  the  "tassel,"  at  the  summit  of  the  culm. 
The  pistillate  spikelets  are  in  pairs,  crowded  in  8  to 
16  rows  (rarely  more)  always  an  even  number,  on  a 
greatly  thickened  compound  axis,  the  "cob/'  borne 
in  the  axils  of  the  leaves  and  enveloped  in  numerous 
leafy  bracts  ("husks"),  the  long  styles  (the  "silk") 
protruding  from  the  summit,  the  whole  called  "tEe 
"ear."  The  staminate  spikelets  (Fig.  81,  C)  are 
much  like  those  of  Tripsacum  and  contain  two 


HIGHLY  SPECIALIZED  UNISEXUAL  SPIKELETS    91 


staminate  florets.  The  pistillate  spikelets  stand  at 
right  angles  to  their  axis,  the  cob  (Fig.  81,  A).  The 
glumes  are  minute,  scarcely  covering  the  ovary  at 
flowering  time  (Fig.  81,  B),  and  in  the  ripened  grain 
remain  as  chaff  on  the  cob,  the  greatly  enlarged 
grain  being  naked. 
This  grain,  "a  kernel 
of  corn,"  remains  on 
the  axis  until  loosened 
by  force. 

Indian  corn  is 
known  only  in  culti- 
vation. The  problem 
of  its  origin  has  not 
yet  been  solved.  We 
only  know  that  it 
originated  somewhere 
in  America,  probably 
on  the  uplands  of 
the  tropics.  It  was 
widely  cultivated  by  the  aborigines  when  the  western 
continents  were  discovered.  The  problem  of  the 
morphology  of  the  ear  of  corn  has  not  yet  been  satis- 
factorily solved,  but  it  is  not  at  all  difficult  to  recog- 
nize the  individual  spikelets,  both  staminate  and 
pistillate. 

The  student  who  has  come  this  far  will  find  it  pos- 
sible to  dissect  the  inflorescence  of  any  of  our  grasses, 
with  the  possible  exception  of  buffalo-grass,  and  to 
distinguish  the  spikelets  and  the  different  organs. 


FIG.  81,  A,  part  of  cross-section  of  an 
ear  of  corn,  Zea  Mays,  showing  two 
pistillate  spikelets  standing  at  right 
angles  to  their  axis  (the  cob);  B,  pis- 
tillate spikelet  about  flowering  time; 
C,  part  of  raceme  of  staminate  spike- 
lets. 


92 


FIRST  BOOK  OF  GRASSES 


Buffalo-grass  (Bulbilis  dactyloides)  is  placed  in  the 
same  tribe  as  the  grama-grasses  (page  57),  but  it  has 
been  left  until  the  last,  so  that  the  student  might  have 
greater  experience  to  draw  on.  It  is  dioecious  (p.  23), 
and  the  staminate  and  pistillate  inflorescences  are 
strikingly  different.  (Recall  Fig.  24,  p.  32). 

Examine  Fig.  82,  B, 
showing  a  pistillate 
spikelet  with  a  small 
narrow  first  glume  and 
a  very  large,  broad,  3- 
toothed  second  glume, 
entirely  infolding  the 
body  of  the  floret.  The 
floret,  removed  from 
the  glume,  is  shown 
in  Fig.  82,  C.  Its  3- 
toothed  lemma  ap- 
proaches in  form  the 


lemma  of  some  of  the 
grama-grasses.    (Com- 


FIG.  82.  A,  pistillate  inflorescence  of 
Bulbilis  dactyloides;  B,  pistillate 
spikelet  cut  from  the  rachis;  C,  pis- 
tillate floret;  D,  diagram  of  half  a 

head,  showing  one  of  the  two  rows     This     pistillate 
of   spikelets;  E,    staminate   inflores-     i    ,  •,    . 

cence;  F,  staminate  spikelet.  *€t  as  presented  IS  not 

at    all    puzzling,    the 

large  thick  second  glume  with  overlapping  edges  en- 
tirely inclosing  the  floret  being  the  only  remarkable 
feature.  These  spikelets,  however,  are  borne  in  the 
curious  inflorescence  shown  in  Fig.  82,  A.  These  little 
hard  white  heads  are  borne,  mostly  two  together,  on 


HIGHLY  SPECIALIZED  UNISEXUAL  SPIKELETS    93 

a  very  short  slender  axis,  in  the  axils  of  broadened 
sheaths  at  the  summit  of  short  culms  and  very  much 
overtopped  by  the  blades.  If  we  cut  off  the  base  of 
one  of  these  little  heads  we  have  three  to  five  such 
spikelets,  as  shown  in  Fig.  82,  B,  which  had  been 
held  rigidly  together  by  the  hard  thickened  base, 
the  overlapping  backs  of  the  second  glumes  forming  a 
thick  white  wall  surmounted  by  their  green-toothed 
summits.  The  base  can  be  nothing  but  a  rachis, 
shortened,  broadened,  and  thickened,  though  all 
trace  is  lost  of  the  junction  of  the  spikelets  and  the 
rachis.  Fig.  82,  D,  is  a  diagram  of  half  a  head,  show- 
ing one  of  the  two  rows  of  spikelets.  Compare  this 
with  Fig.  51,  E,  showing  a  great  number  of  spikelets 
on  an  elongate  rachis.  As  in  Bouteloua  gracilis  the 
spikelets  stand  nearly  at  right  angles  to  the  rachis 
and  the  first  glume  is  inward,  that  is,  it  would  be 
against  the  rachis,  as  in  Bermuda-grass,  if  the  spike- 
lets  were  appressed.  The  difficulty  the  student  en- 
counters in  comprehending  the  pistillate  inflores- 
cence of  buffalo-grass  is  not  so  much  due  to  its 
complexity  as  to  the  difficulty  of  dissecting  the 
rigid  little  structure,  and  also  to  the  suppression 
or  deformity  of  some  of  the  organs.  When  spike- 
lets  are  closely  crowded,  as  in  the  Cenchrus  bur, 
in  some  species  of  millet,  and  in  buffalo-grass,  some 
of  them  are  nearly  always  deformed  from  pressure. 
In  buffalo-grass  one  or  two  of  the  spikelets  hi  a 
head  are  not  fully  developed.  The  first  glume  is 
commonly  reduced  to  a  minute  scale  in  two  or 


94  FIRST  BOOK  OF  GRASSES 

three  of  the  spikelets,   and  sometimes   it   is   sup- 
pressed. 

The  staminate  inflorescence  (Fig.  82,  E)  resembles 
the  spikes  of  grama-grass  (Fig.  51,  E)  but  the  spike- 
lets  (Fig.  82,  F)  are  awnless,  and  the  second  floret  is 

well  developed  and  contains  a  staminate  flower. 

« 

SUMMARY 

In  the  case  of  greatly  modified  structures  the 
different  organs  are  to  be  interpreted  by  their  relative 
position  and  by  their  analogy  to  corresponding 
organs  in  related  grasses. 

REVIEW 

Collect  the  inflorescence  of  Tripsacum  if  available,  disjoint 
it  and  dissect  the  spikelets. 

Examine  a  very  young  ear  of  corn  and  note  that  the  spikelets 
are  always  in  pairs  (consequently  an  ear  of  corn  always  has  an 
even  number  of  rows).  Distinguish  the  glumes  and  lemmas. 
Examine  the  staminate  spikelets. 

If  available,  collect  buffalo-grass  and  dissect  the  staminate 
and  pistillate  inflorescence,  preparing  the  latter  by  boiling  it  a 
few  moment's  in  water  to  which  a  few  drops  of  glycerine  have 
been  added.  When  no  glume  but  the  large  thickened  one  is 
found  in  the  pistillate  spikelet  of  buffalo-grass,  how  do  you  know 
which  glume  that  is? 


FIG.  83. 


DIAGRAMMATIC  SUMMARY  OF  THE  PRIMARY 
CHARACTERS  OF  THE  TRIBES 

SERIES  I— POAT^E 

Spikelets  laterally  compressed;  florets  mostly  falling  from  the 
persistent  glumes 

1.  FESTUCE^J,  fescue  tribe 
Spikelets  many-flowered. 
Glumes  relatively  small. 
Lemmas  awned  from  summit 

or  awnless. 

Inflorescence  a  panicle. 
[Contains  fescues,  brome- 
grasses,  and  blue-grass.] 

2.  HORDED,  barley  tribe 
Spikelets  1-  to  many-flowered, 

sessile  on  opposite  sides  of  a 

jointed    rachis,    forming    a 

spike. 
Rachis  rather  than  spikelets 

specialized. 
Inflorescence  a  solitary  spike. 

[Contains  wheat,  rye,  and 
barley.] 

3.  AVENE.E,  oat  tribe 
Like  Festucese,  but  glumes  en- 
larged and  florets  fewer  in 
number. 

Rachilla  joints  short. 
Lemmas  awned  from  the  back. 
Inflorescence  a  panicle. 
[Contains  oats.] 

95 


FIG.  84. 


FIG.  85. 


96 


FIRST  BOOK  OF  GRASSES 


4.  AGROSTIDE^,  timothy  tribe 

Like  Festucese  reduced  to  its 

lowest    terms;    spikelets    1- 

flowered. 
Lemmas  awnless  or  awned,  the 

awn  from  back  or  summit. 
Glumes      sometimes     awned, 

sometimes  suppressed. 
Inflorescence  a  panicle. 
[Contains  redtop  and 
timothy.] 


FIG.  86. 


5.  CHLORIDES,  grama  tribe 

Spikelets  1-  to  several-flowered, 
sessile  on  one  side  of  a  con- 
tinuous rachis. 

All  but  the  lowest  floret  com- 
monly sterile  and  variously 
modified. 

Inflorescence  of  two  to  several 
1-sided  spikes,  solitary,  race- 
mose or  digitate. 
[Contains  grama-grasses.] 


FIG.  87. 


6.  NAZIE^E,  curly-mesquite 
tribe. 

Spikelets  1-  or  2-flowered,  in 
fascicles,  the  whole  falling 
from  the  main  axis  entire. 

[Not  a  natural  tribe,  some  of 
the  genera  included  not 
being  closely  related.] 


FIG.  88. 


SUMMARY  OF  PRIMARY  CHARACTERS        97 


7.  PHALARIDE^,    canary-grass 
tribe 

Spikelets  with  one  perfect 
floret  and  two  sterile  florets 
below,  these  falling  attached 
to  the  fertile  floret. 

Inflorescence  a  panicle. 

[Contains  canary-grass  and 
sweet  vernal-grass.] 


FIG.  89. 


8.  ORYZE^E,  rice  tribe 

Spikelets     1-flowered,    falling 

from  the  pedicel  entire. 
Glumes  reduced  or  suppressed. 
Inflorescence  a  panicle. 
[Contains  rice.] 


FIG.  90. 


9.  ZIZANIE^E,  Indian  rice  tribe 

Plants  monoecious. 

Spikelets     1-flowered,    falling 


Glu.ne-s  suppressed. 
Inflo^  ycence  a  panicle. 
[   ,ild  or  Indian  rice.] 


98  FIRST  BOOK  OF  GRASSES 

SERIES  IL— PANICAT.E 

Spikelets  dorsally  compressed,  falling  entire,  singly  or  together 
with  parts  of  the  axis. 

10.  PANICE^,  millet  tribe 

Spikelets  with  one  perfect  ter- 
minal  floret   and   a  sterile 

floret  below. 

Rachilla  joints  very  short. 
Glumes   membranaceous,  the 

first    small,    suppressed   in 

some  genera;  sterile  lemma 

like  the  second  glume,  the 

two  appearing  like  a  pair  of 

glumes. 
Fertile  lemma  and  palea  in-  FIG.  92. 

durate. 
Inflorescence  a  panicle  or  of 

one  to  many  racemes,  these 

digitate  or  racemose  on  the 

main  axis. 

[Contains  millets  and  crab- 
grasses.] 


SUMMARY  OF  PRIMARY  CHARACTERS         99 


11.  ANDROPOGONE^J,  sorghum 
tribe 

Spikelets  paired,  one  perfect 
and  sessile,  the  other  sterile 
and  pedicellate,  borne  on  a 
jointed  rachis. 

Fertile  spikelets  with  one  per- 
fect terminal  floret  and  a 
sterile  lemma  below;  falling 
with  joints  of  rachis  and 
sterile  pediceled  spikelet  at- 
tached. 

Glumes  indurate,  inclosing  the 
florets;  lemmas  very  thin; 
palea  often  suppressed. 

[Contains  sugar-cane,  Johnson- 
grass  and  broom-sedges.] 

12.  TRIPS  ACE-*;,  corn  tribe 

Plants  monoecious. 

Pistillate  spikelets  with  one 
perfect  terminal  floret  and  a 
sterile  lemma  below,  falling 
embedded  in  the  joints  of 
the  rachis.  'Persistent  on 
the  thick  compound  axis  in 
Zea.) 

Staminate  spikelets  2-flowered 
in    pairs,    racemose. 
[Contains    gama-grass    and 
Indian  corn.J 


FIQ.  93. 


FIG.  94. 


GENERAL  INFORMATION  FOR  THE  BEGINNER 

It  is  hoped  that  after  completing  the  twelve  les- 
sons the  student  will  be  eager  to  study  and  identify 
the  grasses  of  his  region. 

To  aid  the  beginner  in  the  study  of  the  plant,  the 
following  outline  is  offered,  suggesting  points  to  be 
observed : 

OUTLINE  FOR  STUDY  OF  A  GRASS  PLANT 

Duration — Annual:  Winter  annual,  summer  annual. 

Perennial:    Without    rhizomes    (with    or   without   winter 

rosette) ;  with  rhizomes  (these  short  or  long,  thick,  knotty, 

or  slender) . 
Habit — Erect,  ascending,  prostrate,  geniculate,  creeping,  rooting 

at  nodes,  or  stoloniferous.   Tufted  or  culms  few  or  solitary. 
Culm — Height;  slender  or  robust;  simple  or  branching  (from 

upper  nodes,  lower  nodes,  all  nodes) ;  glabrous,  scabrous, 

or  pubescent  (throughout  or  below  nodes  or  inflorescence) . 
Nodes:  Glabrous  or  pubescent  (hairs  appressed,  spreading, 

retrorse,  i.  e.,  pointing  backward). 
Sheaths:  Close,  loose,  or  spreading;  glabrous  or  pubescent 

(note  margin  and  summit) ;  open  (as  common)  or  closed. 
Ligule:  Length;  membranaceous;  hairy  (stiff  or  delicate); 

obsolete. 
Blades:  Erect  or  spreading,  length  and  width.     Shape: 

Rounded,  clasping  or  narrowed  at  base;  flat,  folded,  or 

involute.     Texture:   Thin,   thick,   rigid,    lax.     Surface: 

Glabrous,  pubescent   (pilose,  villous,  hispid),  scabrous 

(note  each  surface  and  margin). 
100 


GENERAL  INFORMATION'   \  .o     .  ,       101 

Inflorescence — Terminal  only  on  main  culm' and  .branches,  or 
axillary  also.  Simple  or  compound.  'Pa6i6k,  R0$J(2p9&j& 
and  width),  loose  or  compact,  few-flowered  or  many- 
flowered,  nodding  or  erect.  Raceme,  size,  etc.  Spike, 
size,  etc. 

Axis  of  panicle:  Size,  pubescence,  etc.;  branches  solitary, 
fascicled  or  whorled,  flexuous  or  stiff,  ascending,  spread- 
ing or  reflexed. 

Axis  of  raceme  or  spike:  Continuous  or  disjointing;  slender, 

stout,  narrow,  winged;  pubescence. 

Spikelet — Pediceled  or  sessile;  laterally  or  dorsally  compressed; 
falling  entire,  alone,  or  with  joints  of  axis;  florets  falling 
from  the  glumes;  number  of  florets. 

Glumes:  Similar  or  unlike;  size  (compared  to  spikelet,  one- 
half,  one-third,  etc.);  shape,  awned,  toothed,  etc.;  tex- 
ture, nerving,  pubescence. 

Lemma:  Fertile  or  sterile,  size,  shape,  texture,  pubescence. 

Palea:  Flower  bearing  or  empty,  size  (sometimes  obsolete), 
shape,  texture. 

It  will  further  the  student's  self -training  if  he  writes 
down  the  characters  of  the  first  few  grasses  studied 
and  of  any  particularly  puzzling  or  interesting  later 
ones,  making  drawings  of  the  spikelet  and  its  parts 
or  diagrams  of  complicated  inflorescences.  One 
should  not  hesitate  to  make  drawings  merely  because 
he  "can  not  draw."  However  crude  a  sketch  may 
be  it  is  of  great  value,  not  only  as  a  record  of  observa- 
tions, but  for  its  training  in  powers  of  observation. 
The  one  who  " never  could  draw"  is  the  very  one 
who  should  make  frequent  drawings,  however  crude 
they  may  be. 

Anyone  wishing  to  make  a  serious  study  of  grasses 


102  ;  FIRST  BOOK  OF  GRASSES 

should  prepare  an  herbarium,  that  is,  a  collection  of 
plants  pressed  and  dried  in  such  a  way  that  they  may 
be  mounted  by  gummed  straps  to  sheets  of  heavy 
paper  and  arranged  in  folders  for  reference.  Grasses 
so  prepared  keep  indefinitely.  A  circular  giving 
"  Directions  for  preparing  herbarium  specimens  of 
Grasses"  (Bureau  of  Plant  Industry  Document  442, 
1909)  may  be  obtained  without  charge  on  request 
to  the  office  of  the  Systematic  Agrostologist,  Bureau 
of  Plant  Industry,  United  States  Department  of 
Agriculture,  Washington,  D.  C. 

In  studying  grasses  the  first  thing  is  to  understand 
the  structure  of  the  plant  in  hand,  particularly  its 
inflorescence;  the  second  is  to  learn  its  relationship 
to  other  grasses  and  what  name  has  been  applied  to 
it.  The  latter  is  what  is  meant  by  " identifying"  or 
" determining"  a  plant.  Practically  all  the  grasses 
of  the  United  States  are  described  in  one  or  more 
manuals  of  botany  or  state  floras.  Most  of  these 
manuals  give  "keys"  to  genera  and  species.  [The 
word  key  is  used  figuratively — an  instrument  by 
means  of  which  a  way  is  opened.]  A  key  is  an  ar- 
rangement of  contrasting  characters  by  which, 
choosing  one  and  rejecting  the  other,  the  student  is 
led  to  the  name  which  applies  to  the  plant  in  hand. 
For  example,  take  Figs.  23,  27,  45,  48,  65,  and  76, 
and  trace  them  through  the  following  key,  read- 
ing both  of  the  lines  having  like  indention,  these 
giving  the  contrasting  characters  from  which  to 
choose. 


GENERAL  INFORMATION  103 

Spikelets  laterally  compressed,  the  florets  falling  from  the  per- 
sistent glumes. 
Inflorescence  a  panicle,  spikelets  pediceled. 

Plants  dioecious;  spikelets  several-flowered DISTICHLIS. 

Plants  perfect;  spikelets  1-flowered STIPA. 

Inflorescence  a  spike,  spikelets  sessile. 
Spike  solitary;  spikelets  several-flowered,  borne  on  opposite 

sides  of  the  rachis LOLIUM. 

Spikes  several,  digitate;  spikelets  1-flowered,  borne  on  one 

side  of  the  rachis CAPRIOLA. 

Spikelets  dors  ally  compressed,  the  spikelets  falling  entire  or  to- 
gether with  joints  of  the  rachis. 
Spikelets  all  alike,  solitary  (borne  singly)  on  a  continuous 

rachis AXONOPUS. 

Spikelets  of  two  kinds  borne  in  pairs,  one  sessile  and  per- 
fect, the  other  pediceled  and  sterile,  the  rachis  articu- 
lated   ANDROPOGON. 

In  actual  work,  of  course,  one  never  has  so  simple  a 
problem  as  that.  With  exceptions  (such  as  are  noted 
pages  44  and  59)  and  closely  related  genera  and 
species,  it  often  demands  careful  weighing  of  all  the 
facts  to  use  an  extended  key  successfully,  but  it  is 
excellent  training  in  judgment. 

The  name  reached  in  the  key  is  verified  or  rejected 
by  reading  the  description  in  the  text  and  noting  how 
the  characters  of  the  plant  agree  with  those  specified. 
When  the  description  does  not  apply  tt)  the  plant  in 
hand,  one  must  return  to  the  key  and  try  again. 


104  FIRST  BOOK  OF  GRASSES 

BOOKS 

The  plants  one  obtains  for  himself,  and  he  studies 
them  by  means  of  the  few  tools  mentioned  before 
(p.  6).  To  identify  the  plants  requires  books. 

A  recently  published  work,  "The  Genera  of 
Grasses  of  the  United  States,"  by  A.  S.  Hitchcock, 
Bulletin  772,  United  States  Department  of  Agricul- 
ture, giving  keys  to  tribes  and  genera,  descriptions 
and  illustrations  of  all  the  genera,  and  notes  on  the 
more  important  species,  as  well  as  indications  of 
exceptions,  most  helpful  to  the  beginner,  is  the  first 
book  which  the  student  should  acquire.  It  may  be 
obtained  from  the  Superintendent  of  Documents, 
Government  Printing  Office,  Washington,  D.  C., 
at  40  cents  a  copy.  The  farmer,  the  agricultural 
student,  or  the  botanist  who  wishes  only  to  be  able 
to  identify  any  conspicuous  or  useful,  weedy  or 
injurious  grass  of  his  neighborhood  requires  nothing 
more  than  this  and  the  manual  of  botany  covering 
his  region.  The  following  are  the  current  manuals: 

From  Maine  to  Virginia  and  west  to  Minnesota 
and  Missouri,  inclusive:  Gray's  New  Manual  of 
Botany,  7th  edition,  1908  (grasses,  by  A.  S.  Hitch- 
cock) ;  Britton's  Manual  of  the  Flora  of  the  Northern 
States  and  Canada,  3d  edition,  1907  (grasses,  by 
G.  V.  Nash),  extending  west  to  the  western  boundary 
of  Kansas  and  Nebraska;  Britton  and  Brown's 
Illustrated  Flora  of  the  Northern  United  States, 
Canada,  and  the  British  Possessions,  second  edition, 


GENERAL  INFORMATION  105 

1913,  3  volumes  (grasses,  by  G.  V.  Nash,  in  vol- 
ume 1). 

From  North  Carolina  to  Florida  and  west  to 
Oklahoma  and  Texas:  Small's  Flora  of  the  South- 
eastern United  States,  1903  (grasses,  by  G.  V. 
Nash). 

The  Rocky  Mountain  region  and  east  to  the  Black 
Hills  of  South  Dakota:  Coulter  and  Nelson's  New 
Manual  of  Botany  of  the  Central  Rocky  Mountains, 
1909  (this  does  not  cover  the  Mexican  flora  that 
extends  into  southern  New  Mexico  and  Arizona); 
Rydberg's  Flora  of  the  Rocky  Mountains  and  Adja- 
cent Plains,  1917. 

There  is  no  manual  covering  the  flora  of  the  South- 
west, but  Wooton  and  Standley's  Flora  of  New 
Mexico  (Contributions  United  States  National  Her- 
barium, Vol.  19,  1915),  includes  also  most  of  the 
species  of  Arizona.  This  work  gives  keys  to  the 
genera  and  species  and  descriptions  of  the  genera 
but  not  of  the  species. 

California:  Jepson's  Flora  of  California,  1912. 
(Grasses,  by  A.  S.  Hitchcock). 

Washington:  Piper's  Flora  of  the  State  of  Wash- 
ington (Contributions  United  States  National  Her- 
barium, Vol.  11,  1906),  giving  keys  but  not  descrip- 
tions; Piper  and  Beattie's  Flora  of  the  Northwestern 
Coast,  1915,  with  keys  and  descriptions;  and  Piper 
and  Beattie's  Flora  of  Southeastern  Washington  and 
adjacent  Idaho,  1914,  with  keys  and  descriptions. 

Oregon,  Utah,  and  Nevada,  and  most  of  Idaho 


106  FIRST  BOOK  OF  GRASSES 

are  not  yet  covered  by  manuals,  but  manuals  of  ad- 
joining regions  include  most  of  the  species. 

Besides  these  general  manuals  there  are:  Hitch- 
cock's Text-Book  of  Grasses,  1914,  with  illustrations, 
treating  of  economic  grasses  and  their  uses  and  also 
of  the  morphology  and  the  classification  of  grasses; 
Grasses  of  Iowa,  Part  II,  by  Pammel,  Ball,  and 
Scribner  (Iowa  Geological  Survey,  Supplementary 
Report,  1905),  with  keys,  descriptions,  and  illustra- 
tions; Grasses  of  Illinois,  by  Edna  Mosher  (Univer- 
sity of  Illinois  Agricultural  Experiment  Station 
Bulletin  205,  1918),  with  keys,  descriptions,  and 
illustrations;  Manual  of  Farm  Grasses,  by  A.  S. 
Hitchcock,  1921. 

A  helpful  little  bulletin  is  Lyman  Carrier's  "  Iden- 
tification of  Grasses  by  Their  Vegetative  Char- 
acters" (Bulletin  461,  United  States  Department  of 
Agriculture,  to  be  obtained  from  the  Superintendent 
of  Documents,  Government  Printing  Office,  Wash- 
ington, D.  C.,  for  5  cents).  One  should  always  have 
the  inflorescence  for  accurate  identification,  but 
there  are  occasions  when  one  would  be  glad  to  iden- 
tify a  seedling  if  possible. 

One  who  finds  interest  and  delight  in  the  study  of 
grasses  will  want  to  accumulate  a  working  library. 
A  bibliography  of  even  the  most  important  works 
would  be  too  long  to  be  included  here  and  would 
be  out  of  place  in  a  first  book  of  grasses.  How- 
ever, it  may  be  well  to  mention  a  number  of  pa- 
pers on  grasses  that  have  been  issued  in  the  past 


GENERAL  INFORMATION  107 

few  years  by  the  United  States  Department  of 
Agriculture  and  the  United  States  National  Her- 
barium which  can  be  purchased  for  a  small  amount 
from  the  Superintendent  of  Documents  or,  the  few 
out  of  print,  from  dealers  in  second-hand  books. 

Hitchcock,  A.  S.    North  American  Species  of  Leptochloa.    U.  S. 

Dept.  Agr.,  Bur.  PL  Ind.  Bull.  33,  24  pp.,  with  plates. 

1903. 
North  American  Species  of  Agrostis.    U.  S.  Dept.  Agr., 

Bur.  PL  Ind.  Bull.  68,  68  pp.,  with  plates.    1905. 
Mexican  Grasses  in  the  United  States  National  Herbarium. 

Contr.  U.  S.  Nat.  Herb.  17,  pp.  181-389.    1913. 
The  North  American  Species  of  Ichnanthus;  The  North 

American  Species  of  Lasiacis.    Contr.  U.  S.  Nat.  Herb. 

22,  31  pp.,  with  plates.     1920. 
Revisions  of  North  American  Grasses:  Isachne,  Oplis- 

menus,  Echinochloa,  and  Chaetochloa.    Contr.  U.  S. 

Nat.  Herb.  22,  pp.  115-208,  with  text  figures.    1920. 
and  Chase,  Agnes.      The  North  American  Species  of 

Panicum.    Contr.  U.  S.  Nat.  Herb.  15,  396  pp.,  with 

text  figures.    1910. 
Tropical  North  American  Species  of  Panicum.     Contr. 

U.  S.  Nat.  Herb.  17,  pp.  459-539,  with  text  figures. 

1915. 
Grasses  of  the  West  Indies.    Contr.  U.  S.  Nat.  Herb.  18, 

pp.  261-471.    1917. 
Griffiths,  David.    The  Grama  Grasses:  Bouteloua  and  Related 

Genera.    Contr.  U.  S.  Nat.  Herb.  14,  pp.  343-428,  with 

plates.    1912. 
Merrill,  Elmer  D.    North  American  Species  of  Spartina.    U.  S. 

Dept.  Agr.,  Bur.  PL  Ind.  Bull.  9,  16  pp.    1902. 
Piper,  C.  V.    North  American  Species  of  Festuca.    Contr.  U.  S. 

Nat.  Herb.  10,  48  pp.,  with  plates.     1906. 


108  FIRST  BOOK  OF  GRASSES 

Scribner,  F.  L.,  and  Merrill,  E.  D.     The  Grasses  of  Alaska. 

Contr.  U.  S.  Nat.  Herb.  13,  pp.  47-92.    1910. 
Shear,  C.  L.     A  Revision  of  the  North  American  Species  of 

Bromus  Occurring  North  of  Mexico.    U.  S.  Dept.  Agr. 

Div.  Agrost.  Bull.  23,  66  pp.,  with  text  figures.    1900. 
Chase,  Agnes.    The  North  American  Species  of  Brachiaria;  The 

North  American  Species  of  Cenchrus.     Contr.  U.  S. 

Nat.  Herb.  22,  pp.  33-77,  with  text  figures.    1920. 
The  North  American  Species  of  Pennisetum.    Contr.  U.  S., 

Nat.  Herb.  22,  pp.  209-234,  with  text  figures.    1921. 

BOTANICAL   NAMES 

In  the  introduction,  the  reasons  were  given  for 
using  Latin  names  of  plants.  It  will  have  been 
noticed  that  these  names  are  made  up  of  two  words, 
the  generic  name  (a  noun)  and  the  specific  (an 
adjective  or  a  noun  in  the  possessive  case  or  in  apposi- 
tion), and  that  the  generic  name  is  placed  first,  like 
the  surnames  of  persons  in  a  directory. 

Both  words  of  the  name  are  generally  supposed  to 
refer  to  some  characteristic  or  property  of  the  plant 
to  which  it  is  applied,  as  Lepturus  (slender  tail) 
cylindricus  (cylindric)  and  Erianthus  (woolly  flower) 
saccharoides  (like  Saccharum,  that  is,  sugar-cane), 
but  often  botanical  names  do  not  fit  any  better  than 
do  names  of  persons — Paul  (meaning  small)  Baker 
may  be  a  tall  blacksmith,  or  Martha  (meaning  bitter) 
Stern  may  be  sweet  and  gentle.  Many  of  the  Lin- 
naean  genera  bear  the  ancient  classic  Greek  or  Latin 
names,  such  as  Quercus  for  the  oak  and  Ulmus  for 
the  elm.  In  many  other  cases  Linnaeus  used  classic 


GENERAL  INFORMATION  109 

names  but  applied  them,  not  as  anciently  used,  but 
to  a  different  group.  Bromus  to  the  Greeks  was  the 
oat,  but  Linnaeus  used  it  for  the  brome-grasses ; 
Zizanion  was  the  tares  (supposed  to  be  Lolium 
temulentum)  sown  by  the  enemy  among  the  wheat, 
in  the  parable  of  Scripture,  but  Linnaeus  used  the 
feminine  form  of  the  word  for  our  wild  rice.  On  the 
whole,  however,  botanical  names  are  more  or  less 
descriptive,  and  it  is  helpful  as  well  as  interesting  to 
be  mindful  of  their  meaning,  especially  of  the  names 
of  species.  Any  plant  with  the  name  "asper"  or 
"scaber"  will  be  rough  in  some  part;  "pubescens" 
will  be  hairy;  "alba"  will  have  white  flowers  or  bark 
probably,  and  "rubra"  red.  The  name  Bromus 
secalinus  implies  that  the  species  was  a  weed  in  the 
rye  (Secale)  fields  of  Europe,  as  it  is  in  our  wheat 
fields.  Holcus  halepensis  was  known  in  the  early 
ages  from  Aleppo  (Haleb)  in  Syria,  and  Phalaris 
canariensis  from  the  Canary  Islands. 

The  present  system  of  botanical  nomenclature 
dates  from  1753,  when  Linnaeus 's  Species  Plantarum 
was  published,  using  binomials  (names  of  two  words) 
for  all  the  species.  Before  this,  plants  were  given 
phrase  names,  more  or  less  descriptive,  such  as 
"Panicum  with  lax  drooping  panicle,  the  sheaths  of 
the  leaves  pubescent,"  for  proso  millet  (Panicum 
miliaceum)  or  "Grass  with  a  very  long  spike,  like 
cat-tail,"  for  timothy.  These  phrase  names  were 
in  Latin,  of  course.  Linnaeus's  binomial  plan  so 
simplified  the  hitherto  cumbersome  system  that 


110  FIRST  BOOK  OF  GRASSES 

it  was  everywhere   adopted   in   less   than   a  gen- 
eration. 

In  botanical  works  it  will  be  noted  that  plant 
names  are  followed  by  the  initial,  abbreviation,  or 
the  full  name  of  a  person,  as  Poa  pratensis  L., 
Phragmites  communis  Trin.  This  stands  for  the 
name  of  the  person  who  gave  the  plant  the  name, 
L.  for  Linnaeus,  Trin.  for  Trinius.  It  has  often  hap- 
pened that  the  same  species  has  been  given  different 
names  by  men  working  in  various  places  and  not  in 
touch  with  each  other.  In  such  cases  the  name  first 
given  is  the  one  now  generally  used.  It  has  also 
happened  that  two  species  in  a  genus  have  been 
given  the  same  name.  In  this  case  the  name  stands 
for  the  earlier  one  and  the  second  is  renamed.  These 
superabundant  names  constitute  what  is  termed 
synonymy.  (Synonyms  are  two  or  more  names  for 
the  same  thing.)  Superabundant  names  are  also 
due  to  the  fact  that  many  species  when  first  de- 
scribed were  placed  in  genera  to  which  more  intensive 
study  shows  they  do  not  belong.  Triodia  flava,  for 
example,  was  first  named  Poa  flava  by  Linnaeus,  and 
Danthonia  spicata  was  named  Avena  spicata  by  him. 
When  these  species  are  placed  in  Triodia  and  Dan- 
thonia, respectively,  the  name  of  the  original  author 
is  given  in  parenthesis  with  the  name  or  abbreviation 
of  the  person  who  made  the  change  following  it; 
thus,  Triodia  flava  (L.)  Hitchc.,  Danthonia  spicata 
(L.)  DC, 


GENERAL  INFORMATION  111 

CLASSIFICATION    OF   PLANTS 

As  stated  in  the  introduction  (page  2),  the  clas- 
sification of  grasses  is  based  on  the  characters  of  the 
spikelet.  The  classification  of  plants  is  itself  but  a 
human  attempt  to  show  natural  relationship,  and  the 
attempt  is  based  on  knowledge  of  but  an  infinitesimal 
part  of  the  plant  kingdom.  The  plants  occupying 
the  earth  today  are  the  survivors  of  millions  of 
generations.  Countless  forms  have  become  extinct. 
Some  of  these  are  known  from  fossils,  but  far  more 
have  vanished,  leaving  no  record.  Linnaeus  said 
" Nature  never  makes  jumps."  Connecting  links 
exist  or  have  existed  between  the  greatest  extremes. 
When  no  such  link  is  known,  we  conjecture  that  the 
missing  intermediates  are  among  the  countless  ex- 
tinct forms.  Human  minds  approaching  a  given 
problem  from  various  angles  form  different  con- 
jectures; hence  it  is,  that  botanists  of  different 
periods  or  even  of  the  same  period,  have  diverse 
ideas  of  relationships.  The  species  that  Linnaeus 
described  under  Poa,  for  example,  are  today  recog- 
nized as  belonging  in  three  genera  and  his  species  of 
Panicum  in  nine  genera.  As  a  vastly  greater  number 
of  plants  are  known  today,  botanists  have  wider 
knowledge  on  which  to  base  conclusions,  but  the 
main  difference  between  the  Linnaean  and  the 
present-day  idea  of  genera  is  due  to  the  modern 
concept  of  a  genus  as  a  network  of  related  species  as 
contrasted  with  the  earlier  concept  of  a  genus  as  a 


112  FIRST  BOOK  OF  GRASSES 

sort  of  receptacle  built  of  certain  characters  and 
open  to  any  species  having  those  characters.  Lin- 
naeus's  idea  of  Cenchrus,  for  example,  was  primarily  a 
genus  of  bur-grasses,  and,  besides  what  is  now  recog- 
nized as  Cenchrus  (represented  by  Figs.  70  and  71), 
he  included  in  it  a  species  of  Nazia  (Fig.  54)  and  a 
Mediterranean  grass  in  which  the  "bur"  is  composed 
of  the  rigid  lobes  of  the  lemmas  of  the  dense  head  of 
spikelets,  as  well  as  a  plant  that  is  not  a  grass. 

This  brief  explanation  is  offered  to  save  the  begin- 
ner undue  bewilderment  when  he  finds  in  using 
different  books  that  the  standard  excuse  offered  by 
botanists  of  all  times  and  places,  that  the  Latin  name 
of  a  plant  is  the  same  throughout  the  world,  is  not  as 
true  as  could  be  wished. 

It  will  be  noted  hi  using  botanical  works  that  cer- 
tain characters  are  accepted  as  generic,  that  is,  as 
indicating  that  species  having  these  characters  in 
common  belong  to  a  single  genus.  Such  are  the 
5-nerved  keeled  lemmas  of  Poa.  Other  characters, 
sometimes  quite  as  conspicuous,  such  as  the  pu- 
bescence or  want  of  it  in  Poa,  and  the  presence  or 
absence  of  an  awn  in  Bromus  and  Festuca,  are  re- 
garded as  specific,  that  is,  as  differentiating  species. 
It  might  seem  as  though  by  some  revelation  certain 
characters  are  known  to  be  generic  and  others  to  be 
specific.  Such  is  not  the  case.  A  species  consists  of  a 
group  of  individuals  presumably  capable  of  freely 
inter-breeding.  A  genus  is  a  group  of  species  which 
in  the  sum  total  of  their  characters  are  so  much  alike 


GENERAL  INFORMATION  113 

as  to  warrant  the  assumption  that  they  have  had  a 
common  ancestor.  Characters  taken  as  generic  and 
specific  are  analogous  to  theories  or  working  hypoth- 
eses. We  use  them  as  far  as  they  work ;  if  they  do  not 
work,  we  discard  them  for  other  characters.  Botany 
is  a  science  of  living  things,  and  its  problems  can 
never  be  settled  once  for  all.  It  is  this  enduring 
interest  that  makes  it  so  fascinating. 

POSITION    OF    GLASSES    IN    THE    PLANT    KINGDOM 

Flowering  plants  (excluding  the  pines  and  their 
allies)  fall  into  two  rather  distinct  groups,  (1)  mono- 
cotyledons, characterized  by  an  embryo  having  a 
single  cotyledon  and  by  stems  having  woody  fibers 
not  in  layers  but  distributed  through  them  (as  seen 
in  the  cornstalk)  and  not  increasing  in  thickness  by 
age,  and  (2)  dicotyledons,  with  an  embryo  having 
two  cotyledons  and  stems  with  their  woody  fibers 
forming  a  zone  between  pith  and  bark  and  increasing 
in  thickness  by  annual  layers.  Cotyledons  are  the 
seed  leaves.  Anyone  will  have  observed  that  sprout- 
ing corn,  rye,  and  other  grasses  send  up  a  single  leaf 
first,  while  squash,  radishes,  lettuce,  and  morning- 
glories,  for  example,  have  a  pair  of  opposite  seed 
leaves.  Grasses  belong  in  the  first  class,  with  sedges, 
rushes,  lilies,  and  the  like.  They  form  a  highly 
specialized  family  with  a  greater  number  of  species 
than  any  other  except  the  orchids  and  the  com- 
posites (asters,  dandelions,  thistles,  and  their  kinds). 


114  FIRST  BOOK  OF  GRASSES 

Grasses  have  been  so  successful  in  the  struggle  for 
existence  that  they  have  a  wider  range  than  any  other 
family,  occupying  all  parts  of  the  earth  and  exceed- 
ing any  other  in  the  number  of  individuals.  They 
reach  the  limits  of  vegetation  (except  for  lichens  and 
algae)  in  the  polar  regions  and  on  mountain  tops, 
endure  both  cold  and  torrid  desert  conditions,  form 
the  main  part  of  the  vegetation  of  vast  prairies, 
plains,  savannas,  and  steppes  of  both  hemispheres, 
and  occupy  great  stretches  of  marsh  and  tide  flats, 
where  they  are  building  up  dry  land.  Bamboos,  the 
largest  of  grasses,  form  extensive  forests  and  dense 
jungles.  Grasses  range  in  height  from  less  than  an 
inch,  full  grown,  to  over  a  hundred  feet,  and  they 
have  developed  all  manner  of  contrivances  for  the 
dissemination  of  their  seeds. 


GRASSES  IN  RELATION  TO  MAN 

Of  all  plants,  grasses  are  by  far  the  most  important 
to  man.  The  grains  of  wheat,  barley,  rye,  oats,  rice, 
corn,  sorghum,  and  millet  form  the  staple  food  of  the 
greater  part  of  mankind,  while  the  animals  that 
furnish  food  and  labor,  wool,  mohair,  and  leather 
live  principally  on  grasses.  The  grains  are  also 
sources  of  starch,  alcohol,  and  glucose.  Sugar  and 
sirup  are  obtained  from  sugar-cane  and  varieties  of 
sorghum,  and  of  late  years  enormous  quantities  of 
cooking  oil  are  secured  from  the  germ  of  the  corn. 
Grasses  furnish  the  material  for  brooms  and  brushes 


GENERAL   INFORMATION  115 

and  are  an  important  source  of  fiber  for  paper-making 
and  cordage.  Tons  of  essential  oils  used  in  per- 
fumeries are  annually  extracted  from  grasses.  In  a 
great  part  of  Asia  and  Oceanica  bamboo  forms  the 
principal  or  only  timber  for  buildings  and  bridges 
and  furnishes  the  material  for  all  manner  of  tools, 
utensils,  and  furniture. 


INDEX 


Achyrodes,  61 

aureum,  31 
^Egopogon,  62 

tenellus,  61 
Agropyron  repens,  34 
Agrostideae,  96 
Agrostis,  46,  47 

hiemalis,  47 
Alopecurus,  49 

geniculatus,  48 
Amphicarpon  Purshii,  77 
Andropogon,  83 

scoparius,  82 
Andropogonese,  99 
Anthers,  9 
Anthoxanthum,  64,  65 

odoratum,  64 
Aristida,  51,  52 

dichotoma,  51,  52 
Arrhenatherum  elatius,  45 
Avena  fatua,  42 
Avenese,  95 
Awns,  22,  35 
Axonopus  furcatus,  73 

Bamboos,  114,  115 
Barley,  cultivated,  40 

tribe,  95 

wild,  39 
Barnyard-grass,  73 


Beckmannia,  59 

Bermuda-grass,  14,  55,  93 

Binomials,  109 

Blade,  8,  9,  16 

Blue-grass,  Kentucky,  13,  15, 

26 
Botanical  names,  significance 

of,  108 
Bouteloua,  57,  58 

curtipendula,  57,  58 

gracilis,  58,  93 
Brachiaria,  73 
Bromus,  25,  26 

secalinus,  25 
Broom  sedges,  82 
Buffalo-grass,  60,  92,  93 
Bulbilis  dactyloides,  92 
Bunch  grasses,  13 

Calamagrostis,  46,  47 

canadensis,  46 
Callus,  22 
Campulosus,  59 
Canary-grass,  65 

reed,  65 

tribe,  97 

Capriola  Dactylon,  55 
Caryopsis,  10 
Cathestechum,  59 
Cenchrus,  75 


117 


118 


INDEX 


Cenchrus,  continued 

bur,  93 

myosuroides,  76 

pauciflorus,  76 
ChaBtochloa,  75 

Grisebachii,  74 

lutescens,  75 
Cheat,  75 
Chess,  75 
Chlorideae,  96 
Chloris,  57 

latisquamea,  56 
Cinna,  48 
Classification,  111 
Cleistogamous  spikelets,  77 
Corn,  Indian,  90 

tribe,  99 

Cottea  pappophoroides,  27,  28 
Couch-grass,  34 
Crab-grass,  70 
Culms,  8,  14 
Curly-mesquite  tribe,  96 
Cynosurus  cristatus,  30 

Danthonia  spicata,  43 
Dioecious,  23,  32 
Distichlis  spicata,  32 

Echinochloa  Crusgalli,  73 
Eleusine,  54,  55,  56 

indica,  54,  55 
Elymus,  39,  41 

virginicus,  38 
Embryo,  10,  11 
Emmer,  36 
Endosperm,  11 


Erianthus,  82 

saccharoides,  81 
Eriochloa  punctata,  73 

Fescue  tribe,  95 
Festuca  ovina,  26 
Festucese,  85 
Filaments,  9 
Floret,  10,  11 
Flower,  of  grass,  9 

typical,  9 
Foxtail,  green,  75 

yellow,  75 
Fruit,  11 

Gama-grass,  14,  89 
Genus,  5 
Genera,  5,  111 
Generic  characters,  112 
Glumes,  11,  17 
Grain,  10,  11 
Grama-grass,  57,  92,  94 

tribe,  96 
Graminese,  8 
Grass,  description  of,  8 

flower,  10 
Grasses,  bunch,  13 

in  relation  to  man,  114 

position  of,  in  plant  king- 
dom, 113 

sod-forming,  13 
Green  foxtail,  75 

Herbarium,  use  of  a,  102 
Heteropogon,  87,  88 
contortus,  86 


INDEX 


119 


Hilaria  Belangeri,  62 
Hilum,  11 
Holcus,  83,  85 

halepensis,  80 
Holy-grass,  65 
Homalocenchrus,  65 

oryzoides,  66 
Hordese,  95 
Hordeum,  40 

nodosum,  39,  40 

Indian  corn,  90,  91 

-grass,  81 

rice  tribe,  97 
Inflorescence,  18 


Melica  mutica,  29 
Milium  effusura,  50 
Millet  tribe,  77,  98 
Millets,  75 
Monoecious,  23 
Morphology,  2 
Muhlenbergia  foliosa,  50 
Schreberi,  50 

Nazia  aliena,  63 

Nazieae,  96 

Nodes,  8 

Notholcus  lanatus,  44,  49 


Johnson-grass,  80 


Oat,  45 

tribe,  95 
Oats,  wild,  42 
Oryza  sativa,  65,  66 

Kentucky  blue-grass,  13, 15,  26      Oryzese,  97 

Oryzopsis,  50 

racemosa,  51 
Ovary,  9,  10 
Ovules,  10 


Leaves,  15 
Lemma,  10,  11,  17 
Leptochloa,  59 
Lepturus,  84 

cylindricus,  36 
Ligule,  8,  9 
Lodicules,  9,  10 
Lolium  multiflorum,  36 
Luziola,  67 
Lycurus  phleoides,  49 


Maize,  90 
Manisuris,  83,  84,  90 

cylindrica,  83 
Manuals  of  botany  in  current     Pedicel,  18 

use,  104  Pericarp,  47 


Palea,  10,  11 

Panicatse,  98 

Panicese,  77,  98     f 

Panicle,  18 

Panicularia  septentrionalis,  27 

Panicum,  69,  70,  71 

miliaceum,  69 

Pappophorum  vaginatum,  29 
Paspalum,  71,  73 
,  71 


120 


INDEX 


Petiole,  16 
Phalaridese,  97 
Phalaris  arundinacea,  65 

canariensis,  65 

minor,  65 

Phleum  pratense,  48 
Phragmites  communis,  28 
Pistils,  9,  10 

Pleuropogon  californicus,  27 
Poa,  26 

pratensis,  14,  26,  27 
Poacese,  8 
Poatse,  95 
Prophyllum,  17 

Quack-grass,  15,  34 

Raceme,  18 
Rachilla,  11 
Rachis,  18 
Reed,  28 

canary-grass,  65 
Reimarochloa,  72 
Rhaphis,  85,  88 

pauciflora,  85,  86 
Rhizomes,  13,  14 
Rice,  65,  66 

tribe,  97 

wild,  66 
Rootstocks,  13 
Rye-grass,  38 
Rytilix,  84,  85 

granularis,  84 

Saint  Augustine-grass,  72 
Salt-grass,  32 
Sand-bur,  75,  76 


Scleropogon  brevifolius,  32,  33 

Seneca-grass,  65 

Sheath,  8,  9 

Sitanion,  39 

Sod-forming  grasses,  13 

Sorghastrum,  81 

Sorghum,  80,  82 

tribe,  99 
Spartina,  59 
Spathes,  82 
Sphenopholis,  45 
Spike,  18 

Spikelet,  11,  17,  19 
Sporobolus  airoides,  47 

heterolepis,  48 
Stamens,  9,  10 
Stenotaphrum,  72,  73 

secundatum,  72 
Stigma,  9,  10 
Stipa,  51,  52,  88 

spartea,  51 
Stolons,  14 
Styles,  9,  10 
Sugar-cane,  81 
Sweet  vernal-grass,  64 
Synonyms,  110 
Syntherisma,  73 

sanguinalis,  70 

Timothy,  48 

tribe,  96 
Torresia,  65 
Tribes,  primary  characters  of, 

95 

Triodia  flava,  27,  28 
Tripsacese,  99 


INDEX 


121 


Tripsacum,  90 

dactyloides,  14,  89 
Trisetum,  43,  46 

spicatum,  43 
Triticum  sestivum,  35 

dicoccum,  36 

Vanilla-grass,  65 
Velvet-grass,  44 


Wheat,  35 
Wild  oats,  42 

rice,  66 
Yard-grass,  54 
Yellow  foxtail,  75 

Zea  Mays,  90,  91 
Zizania  palustris,  66 
Zizaniese,  97 
Zizaniopsis  miliacea,  67 


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